Make cookies x yuan and drinks y yuan.
Yes, X+Y > 10...( 1)
0.8X+Y+ 1.6= 10...(2)
Simplified to 0.8X+Y=8.4.
X+ 1.25Y= 10.5
The formula of combination (1) is 0.25 y.
Y & lt2
X is an integer, so X = 9 and Y = 1.2.
(2) The construction team plans to excavate at least 600 cubic meters of earthwork in 10 days. After completing the cube of 120m in two days, it is required to complete the excavation task two days in advance. How much earthwork will be dug at least every day in the next few days?
In the next few days, at least x cubic meters of earthwork will be excavated every day on average.
( 10-2-2)x≥600- 120
x≥80
(3) A school held a summer camp in the summer vacation. When arranging students' accommodation, there are more than 9 people in each room, so some rooms are arranged for 8 people, so the ratio of 7-person rooms to 8-person rooms is 2: 3, and the number of students attending the summer camp is asked.
Analysis: keep the total number of people unchanged, because there is a proportion, you can directly set the unknown number with the comparison column, which is convenient for answering.
Solution:
According to the meaning of the question, there are 2X rooms for 7 people, 3X rooms for 8 people and 5X rooms for * * *.
2X*7+3X*8=5X*7+9
Solution: X=3
So * * * has 5*3= 15 rooms, which means the total number of people is15 * 7+9 =114.
[Or: Room for 7 people * * with 2*3*7=42 (people).
For an eight-person house, 3*3*8=72 (persons).
So there are 42+72= 1 14 (people)] students attending the summer camp.
A: The students who participated in this summer camp are 1 14.
(4) A clothing factory processes a batch of suits, but there is no 15m wool, so 10 tops or 13 pants can be cut. The existing wool is 345 meters. How many meters should the wool of the coat and trousers be cut in order to match them?
1. Cut pants x meters and clothes y meters.
x+y=345
10x/ 15 = 13y/ 15
To solve this system of equations:
x= 195
y= 150
(5) The distance between A and B is 20km, and A and B start at the same time. If the two directions meet in opposite directions and walk in phase after two hours, A will catch up with B after 10 hours. Find the speed of a and b! !
2. Let the speed of A be x kilometers per hour and the speed of B be y kilometers per hour.
10x+ 10y=20
10x- 10y=20
The solution is x = 2 and y = 0.
(6) The two trains leave from two relative locations 9 10 km apart at the same time, and turn after 10 hour; If the first train leaves 4 hours and 20 minutes earlier than the second train, then meet the second train after 8 hours and find the speed of the two trains.
1. solution: let the speed of the first train be x and the speed of the second train be y.
10(x+y)=9 10
8y+37/3x=9 10
(7) There are two kinds of barrels for rice, five big barrels plus 1 small barrel can hold three Jin of rice, and 1 big barrel plus five small barrels can hold two Jin of rice. How many kilograms can 1 vat and 1 keg hold respectively?
Solution: let the big barrel take X-welcome and the small barrel take Y-welcome.
5x+y=3
x+5y=2
(8) A jar has 65,438+0 sides and 2 bottoms. If 1 piece of iron sheet is used as the side of the can, 16 pieces can be used, and 43 pieces can be used as the bottom of the can. Now there are 75 pieces of iron. * * * How many cans can you make theoretically?
Solution: Let there be X on the side and Y on the bottom.
x=2y
1/ 16x+ 1/42y = 75
(9) The length of the express train and the local train are180m and 225m respectively. If driving in the same direction, it takes 8 1s to catch up with the local train from the express train to completely exceed it. If the speed of the express train and the local train are x m/s and y m/s respectively, then the equation representing the equality relationship can be listed as?
8 1(x+y)=225+ 180
(10) I bought 10 stamp, 20 stamps and 50 stamps with 3 yuan 50 * *18 stamp. The total face value of 10 stamp is the same as that of 20 stamps. How many stamps did I buy each of these three stamps?
10 points x ~20 points 1/2X ~50 points 18-X- 1/2X
10 * X+20 * 1/2X+50 *( 18-X- 1/2X)= 350
(1 1) It is known that 3 kilograms of liquor C is made of 70% alcohol of liquor A and 55% alcohol of liquor B. How many kilograms does each liquor need?
Answer: 1 kg liquor a and 2 kg liquor b.
(12) An old man intends to divide his inheritance in the following ways:
Eldest brother gets 100 yuan, and the remaining 10% inheritance.
The second child is divided into 200 yuan, and the remaining legacy is 10%.
Old 3 points 300 yuan, the remaining legacy 10%.
Old 4 points 400 yuan, remaining legacy 10%.
...........................
As a result, every son got the same amount of money. How many sons does the old man have? (9)
(13) I bought 30 notebooks at a unit price of 0.40 yuan. 16 yuan bought 0.80 yuan. How many books did I buy?
Answer: 0.40 yuan for 20 copies, 0.80 yuan 10 copies.
(14) 1. The students in the first group are divided into several pencils. If four of them each take four, and the rest each take three, there is still 16; If 1 person only takes 2 sticks, the others each take 6 sticks. How many students are there? How many pencils are there?
There are x students in the first group? * * * There are y pencils.
Equation y=4*4+(x-4)*3+ 16.
y= 1*2+(x- 1)*6
Answer x=8 y=44
(15) The distance between A and B is 36 kilometers. A walks from A to B, and B walks from B to A ... They set out at the same time and met four hours later; After 6 hours, A left twice as far as B. What was the speed of two people?
Let a speed be xkm/h and b speed be ykm/h.
4(x+y)=36
36-6x=2*(36-6y)
x+y=9
36-6x-72+ 12y=0
x+y=9
-6x+ 12y=36
x=4 y=5
A: A's speed is 4 kilometers per hour, and B's speed is 5 kilometers per hour.
(16) The vegetable company bought a vegetable 140 tons, and prepared to process it and put it on the market. The company's processing capacity is 6 tons/day or 16 tons/day. It is planned to complete the processing task in 15 days. How many days does the company have to arrange for rough machining and fine machining to complete the task on schedule? If the profit per ton of vegetables after rough processing is 1000 yuan, and it is 2000 yuan after fine processing, how much can the company earn by selling these processed vegetables according to this arrangement?
X-day finish machining, y-day rough machining,
x+y= 15
6x+ 16y= 140
The solution is x= 10.
y=5
10*6=60,5* 16=80
60*2000= 120000,80* 1000=80000
120000+80000=200000
(17) A milk processing factory has 9 tons of fresh milk. If it is directly sold in the market, it can make a profit of 500 yuan per ton, 1200 yuan per ton and 2000 yuan per ton. The production capacity of this factory is as follows: if it is made into yogurt, it can process 3 tons a day, and if it is made into milk tablets, it can process 65438 yuan a day.
Option 1: Make as many pieces of milk as possible and sell the rest directly.
Option 2: Make part of it into milk slices and the rest into yogurt for sale, which will be completed in exactly 4 days.
Which scheme do you think is the most profitable? Why?
Scheme 1: 4 tons of milk slices and 5 tons of fresh milk.
Profit: n1= 4 * 2000+5 * 500 =10500.
Scheme 2: 1 ton of milk tablets and 8 tons of yogurt.
Profit: N2 =1* 2000+8 *1200 =1600.
Option 2 is more profitable.
(18) 1. Last year, two workshops of a factory planned to achieve a tax profit of 7.2 million yuan. Thus, workshop A completed the planned tax profit 1 15%, workshop A completed the planned tax profit 1 10%, and the two workshops completed the tax profit of 865438+.
Suppose a overfulfilled X B overfulfilled y.
x+y=8 12-720
x/( 1 15%- 100%)+y/( 1 10%- 100%)= 720
y=32 x=60
(19) has two digits. If you expand each number twice and subtract 4 from the ten digits, the number is 1 of the original two digits. If you exchange each digit with ten digits, the two digits you get are 9 less than the distant two digits, and you can find the two digits.
.
Set the number of digits to x and the number of digits to y.
According to the meaning of the question, y ≥ 5 x ≤ 4; And because "if you change every number into ten numbers, these two numbers are 9 less than the distant two numbers", so X-Y≤ 1.
So: x = 4 y = 5 This number is 54.
(20) In the school volleyball league, four classes in the same group play a single round robin, and the last class is eliminated. If the last few classes are tied, they won't be eliminated before the play-off. Will it definitely appear? Why?
Four classes in the same group play single round robin, and each team has to play three games.
A total of 3*4/2=6 games.
1 class can guarantee not to be eliminated before the play-off!
There are only six victories in all. Suppose 1 class is eliminated before the play-off. Then the other three classes will win at least two games. There are only six victories in all. So it's impossible.
1 class can guarantee not to be eliminated before the play-off.
You may be unqualified.
Because there are only six victories together, if one of the four teams wins three games, it means winning the other three classes. The other three teams only won 1 game. In this way, there will be a play-off between the three teams. . .
Geometry problems are not easy to write ~ ~ they are all found on the web page ~ ~