1. A gas station can fill two cars at the same time. The time required to refuel all kinds of cars is: 7 minutes for big cars, 4 minutes for small cars, 6 minutes for medium-sized cars and 2 minutes for motorcycles. Now there are four different cars coming to the gas station to refuel at the same time. How long does it take for these four cars to refuel? (including waiting time)

2. Someone walks 4.8 hours kilometers per hour. It takes 8.5 minutes less to ride a bike per kilometer than to walk. What's the speed of cycling?

3. There are two engineering teams, Team A and Team B. Team A has twice as many people as Team B. After Team A transferred 9 people and Team B transferred 18 people, Team A gave up. How many people are there in Team A?

4. East warehouse stores 1500 tons of grain, and west warehouse stores 1200 tons of grain. If 60 tons of grain are transported from Dongcang to Xicang every day, how many days later will the grain stored in Xicang be twice as much as that in Dongcang?

Aunt Zhang asked the ages of three young workers.

Xiao Liu said: "I am 22 years old, two years younger than Chen Xiao and older than Xiao Li 1 year."

Xiao Chen said, "I'm not the youngest. Xiao Li is three years older than me and Xiao Li is 25 years old. "

Xiao Li said, "I am younger than Xiao Liu, who is 23 years old and Chen is 3 years older than Xiao Liu."

Three young workers like joking. One of the three sentences each of them said was wrong. Ask Aunt Zhang to help analyze their ages.

6. It is known that the sum of two natural numbers is 60, and the sum of the greatest common factor and the smallest common multiple is 84. What are these two numbers?

7. There are 6 different Chinese books, 4 different foreign language books and 3 different math books on the bookshelf. How many different choices do you have for a Chinese book, a foreign language book and a math book?

8. A class of students planted trees, 100 Chinese fir seedlings and poplar seedlings. Each group was divided into 6 Chinese fir seedlings and 8 poplar seedlings. In this way, the Chinese fir seedlings have just been beaten, and there are two poplar seedlings left. How many Chinese fir seedlings and poplar seedlings are there?

9. Bus length 190 meters, truck length 240 meters. The two cars are traveling at a speed of 20 meters and 23 meters per second respectively. On the double-track railway, how many seconds does it take to meet from the front to the rear?

10. Xiaoxi bought coconuts and mangoes, * * used 43 yuan, 7 yuan for coconuts and 5 yuan for mangoes. She bought coconuts and mangoes, both round numbers. So he bought coconuts and mangoes.