1. Aunt Wang bought 45 kilograms of flour and 70 kilograms of rice and paid it to 480 yuan. It is known that the price of 1 kg flour is twice that of 1 kg rice. What's the price of flour and rice?

Let the prices of flour x and rice y,

45x+70y=480，x=2y

X=6，y=3。

(Method 2,

You don't have to set xy,

To put it bluntly, because the price of 1kg flour is twice that of 1kg rice, 480 yuan can buy 45*2+70kg rice, so rice =480/(45*2+70)=3 yuan/kg, and flour 6 yuan/kg).

2. It takes 74 minutes to manufacture three type A parts and five type B parts in Li Shifu, and 72 minutes to manufacture four type A parts and four type B parts. How many minutes does it take Master Wang to make 10 A parts?

Can be set to a part, a part of x minutes, a part of b minutes and y minutes.

3x+5y=74，4x+4y=72，x=8，y= 10。

You can also do this without setting an unknown number:

Four parts in A and four parts in B need 72 minutes, so 1 parts in A and 1 parts in B need 18 minutes.

So three parts A and three parts B need 54 minutes, so two parts B need 74-54=20 minutes.

Therefore, it takes 20/2 = 10 minutes to make 1 B parts, and 18- 10=8 minutes to make10 parts.

An explorer spent six days crossing the desert on foot. If porters carry food and water for a person for four days, how many workers should explorers hire at least?

I don't understand this question. Does every worker have to accompany the explorer from beginning to end these six days? Can the explorer bring some food and water by himself? Can't he eat half of all the food and starve the porters?

4. During the period of War of Resistance against Japanese Aggression, an armed force behind enemy lines divided 169 into 37 battle groups, with 3 men, 5 men and 7 men respectively. The number of groups in the three-person group and the five-person group is the same. How many groups are there in each of the three battle groups?

I have tried this question one by one. Since the number of groups of three to five is the same, we only need to subtract the multiple of 7 from 169 to see if the remainder is divisible by 8.

For example,169-7 *1=162 is not an integer multiple of 8, so keep trying 169-7*3. . .

Until 169-7*7= 120,18 = 15, so there may be seven groups of seven people, and each group of three or five people has15, which is a * * 7+/kloc.

169-7* 15=64, 64/8=8, so the second possibility is 15 with 7 people, 3 people and 5 people with 8 groups respectively, that is, a * * *15+8 = 3/kloc.

169-7*23=8, 8/8= 1, so the third possibility is that there are 23 groups of 7 people, with 3 people and 5 people in each group having 1, that is, a * * * 23+ 1 = 25 groups.

In addition, 169 people are divided into 37 battle groups, so there are 7 battle groups with 7 people, and 15 is 3 people and 5 people respectively.

Some people take part in labor, some carry soil, and some carry it. A total of 33 poles and 58 baskets are needed. How many people carry dirt and how many people carry dirt?

I'm not familiar with this kind of productive labor scene. Should two baskets be hung on a pole? But 33*2 is greater than 58, please consult an experienced person.

6. Two people ride bicycles along a 3000-meter-long lake. If they travel in the opposite direction, they will meet every five minutes. If they travel in the same direction, A will catch up with B every 60 minutes. What's the speed of A?

Let a speed be x m/min and b m/min (implying that the lake is round and the speed is directional).

5*(x+y)=3000，60(x-y)=3000，x=325，y=275。

7. Some chickens and kittens are playing on the threshing floor. They are 144 feet and 47 heads. How many chickens and kittens are there?

Set up x chickens and y kittens.

X+y=47，2x+4y= 144，x=22，y=25。