Solution: If A can hold X tons and B can hold Y tons, then
2x+3y= 15.5
5x+6y=35
Get x=4.
y=2.5
Get (3x+5y)*30=735。
2. A commodity is now reduced in price 10% for promotion. In order to keep the total sales amount unchanged, how much is the sales volume increased over the original price?
Solution: Increase X% when selling at the original price.
( 1- 10%)*( 1+X %)= 1
x % = 1 1. 1 1%
In order to keep the total sales amount unchanged, the sales volume increased by11.11%compared with the original price.
3. 10% reduced 1 product price is just over half of the original price. 40 yuan, what is the original price of this product?
Solution: Let the original price be X yuan.
( 1- 10%)x-40=0.5x
x= 100
A: original price 100 yuan.
4. There is 40 grams of salt water with 8% salt. How many grams of salt does it take to make salt water with a salt content of 20%?
Solution: suppose x grams of salt is added.
At first, the pure salt was 40 * 8% g.
Add x grams to make 40 * 8%+X.
Salt water is 40+x grams.
Concentration 20%
So (40*8%+x)/(40+x)=20%.
(3.2+x)/(40+x)=0.2
3.2+x=8+0.2x
0.8x=4.8
x=6
So add 6 grams of salt.
In the market, the sales of eggs are priced according to the quantity. A vendor bought a batch of eggs at a price of 0.24 yuan each, but accidentally broke 12 eggs in the process of selling. The remaining eggs are sold at 0.28 yuan each, and the result is still 1 1.2 yuan's profit. How many eggs did the vendor buy at first?
Solution: Suppose the vendor bought X eggs at first.
List the equations according to the meaning of the question:
(X- 12)* 0.28-0.24 X = 1 1.2
0.28 x-3.36-0.24 x = 1 1.2
0.04X= 14.56
X=364
A: The vendor bought 36 eggs at first.
6. To transport 29.5 tons of coal, transport it three times by a truck with a load of 4 tons, and transport the rest by a truck with a load of 2.5 tons. How many times will it take to complete?
It takes x times to complete.
29.5-3 * 4 = 2.5 times
17.5=2.5x
x=7
Seven more shipments are needed to complete.
7. The trapezoidal site covers an area of 90 square meters, with an upper bottom of 7 meters and a lower bottom of 1 1 meter. How high is it?
Its height is x meters.
x(7+ 1 1)=90*2
18x= 180
x= 10
Its height is 10 meter.
8. A workshop plans to produce 5480 parts in April. It has been in production for 9 days, and 908 more are about to complete the production plan. How many pieces will be produced on average every day in these 9 days?
During these 9 days, X was produced every day on average.
9x+908=5408
9x=4500
x=500
During these nine days, an average of 500 were produced every day.
Two cars, A and B, walked in opposite directions at the same time from two places 272 kilometers apart. Three hours later, the distance between the two cars is still17km. A travels 45 kilometers per hour, and B travels how many kilometers per hour?
B travels x kilometers per hour.
3(45+x)+ 17=272
3(45+x)=255
45+x=85
x=40
B is driving at a speed of 40 kilometers per hour.
10 There are two classes in the sixth grade of a school, and the average score in mathematics last semester was 85. There are 40 students in six classes (1) with an average score of 87. 1. There are 42 students in Class Six (2). What is the average score?
The average score is X.
40*87. 1+42x=85*82
3484+42x=6970
42x=3486
x=83
The average score is 83 points.
1 1. The school bought 10 boxes of chalk. 250 boxes were used, and there are 550 boxes left. How many boxes are there on average?
Average x boxes per box
10x=250+550
10x=800
x=80
80 boxes per box on average.
/kloc-Grade 0/2, Grade 4, 200 students. During extracurricular activities, 80 girls went to jump rope. The boys are divided into five groups to play football. How many people are in each group?
There are x people in each group on average.
5x+80=200
5x= 160
x=32
There are 32 people in each group on average.
13. The canteen delivered 150 kg of rice, which was 30 kg less than the flour delivered. How many kilograms of flour does the canteen send?
The canteen brought x kilograms of flour.
3x-30= 150
3x= 180
x=60
The canteen brought 60 kilograms of flour.
14. There are 52 peach trees and 6 rows of pear trees in the orchard. There are 20 more pear trees than peach trees. How many pear trees are there in each row on average?
There are x pear trees per row on average.
6x-52=20
6x=72
x= 12
There are 12 pear trees in each row on average.
15. The area of a triangular piece of land is 840 square meters, the bottom is 140 meters, and the height is how many meters?
The height is x meters.
140x=840*2
140x= 1680
x= 12
The height is12m.
16, Li Shifu bought 72 meters of cloth, just to make 20 clothes for adults and 16 clothes for children. Adult dresses are 2.4 meters each, and how many meters are children's dresses?
Each piece of children's clothing is made of x meters.
16x+20*2.4=72
16x=72-48
16x=24
x= 1.5
Each piece of children's clothing1.5m.
17, three years ago, my mother was six times older than my daughter. This year, my mother is 33 years old. How old is my daughter?
My daughter is x years old this year.
30=6(x-3)
6x- 18=30
6x=48
x=8
My daughter is 8 years old this year.
18. How long will it take for a car with a speed of 50 kilometers per hour to catch up with a car with a speed of 40 kilometers per hour that left two hours ago?
It takes x time
50x=40x+80
10x=80
x=8
It takes eight hours.
19, Xiaodong bought 3kg of apples and 2kg of pears from the fruit shop * * *, and paid 15 yuan. 1kg apples are more expensive than 1kg pears in 0.5 yuan. How much are apples and pears per kilogram?
Apple x
3x+2(x-0.5)= 15
5x= 16
x=3.2
Apple: 3.2
Pear: 2.7
20. Two cars, A and B, leave from A and B at the same time in opposite directions. A travels 50 kilometers per hour, B travels 40 kilometers per hour, and A reaches the midpoint 1 hour earlier than B. How many hours does it take for A to reach the midpoint?
X hours to reach the midpoint.
50x=40(x+ 1)
10x=40
x=4
A reaches the midpoint in 4 hours.
2 1, Party A and Party B set out from A and B at the same time, face to face, and meet two hours later. If A starts from place A and B goes in the same direction at the same time, then A will catch up with B after 4 hours. Given that the speed of A is 15km/, find the speed of B. ..
Speed x of b
2(x+ 15)+4x=60
2x+30+4x=60
6x=30
x=5
B's speed 5
22. Two ropes with the same length, the first one was cut15m, and the second one was 3m more than the remaining three times of the first one. How long are these two ropes?
It turns out that these two ropes are each x meters long.
3(x- 15)+3=x
3x-45+3=x
2x=42
x=2 1
It turns out that the two ropes are each 2 1 m long.
23. A school bought seven basketballs and 10 soccer balls and paid 248 yuan. As we all know, the price of each basketball is equivalent to the price of three footballs. How much is basketball and football each?
Every basketball x
7x+ 10x/3=248
2 1x+ 10x=744
3 1x=744
x=24
Each basketball: 24
Each football: 8