Suppose there are x science and technology books, then there are 4X literature and art books ... and then there are
4x+x = 630，x = 126，4x = 504。
Suppose you buy y science and technology books, then (126+y): 504 = 3: 7, and you get (126+y) = 2 16, y = 90.
There are 120 students in three classes of grade six in a school. The total number of Class A and Class B accounts for 7/ 10 of the total number of sixth-grade students, and the ratio of Class B to Class C is 10: 9. How many students are there in Class A?
The total number of students in Class A and Class B accounts for 7/ 10 of the total number of students in Grade 6, and the number of students in Class C accounts for 3/ 10 of the total number of students in Grade 6, that is, 36 students.
The number of students in Class B and Class C is 10: 9, so there are 40 students in Class B. ..
A = 44 There are 120-40-36 students.
Party A and Party B each deposit a few dollars. It is known that 65438+ 0/4 of Party A's deposit is equal to 2/5 of Party B's deposit. B saves less than A1How much does 200 yuan B save?
Suppose A saves 8 yuan, then B saves 5 yuan.
Then B is 3x less than A =1200 yuan, and X = 400.
B deposit 5x = 2000 yuan.
For a rope, the ratio of the length of the rope used for the first time to the length of the remaining rope is 2: 5, and the second time is less than the first time12m, leaving 48m. How long is this rope?
Assuming the original Xm, what about X-X? (2/7)-【X？ (2/7)- 12] = 48，x = 140。
There is a batch of flour in the canteen. On the first day, 1/4 of all the flour was eaten. The ratio of flour eaten on the second day and the first day was 5: 4, leaving 35 kilograms. How many grams is this batch of flour?
If you eat 5X flour the next day, you will eat 4x flour the first day. So the total flour is 16X.
So 16x-9x = 7x = 35kg, and the total flour is 16x = 80kg.
There are three piles of colored balls in the children's activity center, * * * with 140 kg. It is known that the number ratio of the first pile to the second pile is 2: 3, and the number ratio of the second pile to the third pile is 4/ 15: 1/3. So how many are there in each of the three piles?
It should be 140.
One: two = two: three.
Two: three = 4/ 15: 1/3.
So one: two: three = 8: 12: 15.
1: 8× 140 ÷ 35 = 32
2: 12× 140 ÷ 35 = 48
Three: 15× 140 ÷ 35 = 60
A total of oranges, apples and pears 154 tons were shipped from the fruit market, among which apples were more than oranges 14 tons, and the tonnage ratio of apples to pears was 5:2. Find the tonnage ratio of oranges, apples and pears to be shipped.
Let pear 2X and apple 5X, then orange 5x- 14.
2X+5X+5X- 14= 154
12X= 168
X= 14
Pear 28, apple 70, orange 56
During the summer vacation, Honghong and Huahua went to the countryside to experience life. They helped farmers plant 65,438+008 cabbages. The number of mangroves is 1/4, 9 more than that of flowers. How many trees have Honghong and Huahua planted?
Assume that the number of mangroves is X and the number of species in China is108-X.
Namely: 0.25x-0.2 (108-x) = 9,
0.25X+0.2X-2 1.6=9
0.45 times =30.6
X = 68, red species 68 and China species 40.
The number of students in three classes of grade six in a school is equal, the average number of boys in class two is equal to that of girls, and the number of boys in class three is 2/5 of all boys. What is the proportion of the total number of girls in the whole grade?
(Haha, this topic is a bit interesting)
The number of boys in Class One of Grade Six is equal to that of girls in Class Two, while the number of girls in Class Three is equal.
So it's class one boys = class two girls, class two boys = class one girls, that is, class one boys = class one girls.
Design: There are 2X boys in Class Three. Then all the boys are 5X, and the boys in Class 1 and Class 2 are 3X. So there are three girls in Class One and Class Two. Category III *** 18X.
Boys are 5X and girls are 13X. So the ratio of the number of girls to the number of students in the whole grade is 13: 18.
Party A, Party B and Party C each have a 54 yuan. Whoever spends 3/5 of his own money, Party B uses 3/4 of his own money and Party C uses 2/3 of his own money, and each person buys a pen with the same price. How much money do they have?
Set the pen to 6X yuan. Then:
A: 6x ÷ 3/5 = 10x，B: 6x ÷ 3/4 = 8x，C: 6x ÷ 2/3 = 9x。
∴ 10x+8x+9x = 54 yuan, x = 2.
∴ A has 20 yuan, B has 16 yuan and C has 18 yuan.
When Party A and Party B went shopping in the supermarket, * * * brought 108 yuan. Party A used 75% of his own money, Party B used 4/5 of his own money, and the rest was exactly the same. How much did Party A and Party B originally bring?
Let the rest of the money be x yuan.
Then A's money is 4X. B's money is 5X.
9X= 108, X= 12 .a's money is 4x = 48 yuan. 5x for B = 60 yuan.
The journey is divided into three sections: uphill, flat and downhill. The ratio of the length of each section is 1: 2: 3, and the ratio of the time taken by someone to walk each section is 4: 5: 6. It is known that his speed when going uphill is 3 kilometers per hour and Lu Changquan is 60 kilometers long. How long did it take people to walk the whole distance?
The ratio of the length of each segment is 1: 2: 3 in turn.
Luchangquan is 60 kilometers long, so the uphill road 10.
Time is 10 ÷ 3 = 10/3 hours.
The proportion of time spent on each trip is 4: 5: 6 in turn.
So it takes 50/ 12 hours to level the road, and 5 hours to go downhill.
The whole journey takes10/3+50/12+5 =12.5 hours.
In the 10 km race, when A reaches the finish line, it is ahead of B 2km and C 4km. When B runs to the finish line, how many kilometers is C from the finish line?
When A runs to the finish line, the distance B runs is 10-2 = 8km, and C is 6km.
Let this time take x, the speed of b is 8/X, the speed of c is 6/x..b The speed ratio is A = 4: 3.
2×3/4 = 1.5 km.
4- 1.5 = 2.5 km.
2.5 kilometers to go.
Master and apprentice made 84 parts together. The master makes one in 5 minutes and the apprentice makes one in 9 minutes. How much did the master and apprentice do respectively?
The master makes one in 5 minutes and the apprentice makes one in 9 minutes.
So every 45 minutes, the teacher does 9 and the apprentice does 5. *** 14.
84÷ 14=6。 So * * * did six 45 minutes. That is, the teacher made 6 * 9 = 54; 5 * 6 = 30 acts.
It takes 18 hours for a batch of parts to be processed by Master Zhang alone, and 15 pieces per hour. Now Master Zhang and are dealing with it at the same time. After completion, the ratio of the number of machined parts is 8:5. How many parts are there in this batch?
At the same time, the proportion of people handled by two people is 8:5, that is, the time is the same.
So Master Zhang processes 15× 8/5 = 24 pieces per hour.
It takes 18 hours for Master Zhang to process alone, so there are 432 pieces.