1. The kindergarten teacher gave candy to the children, each with seven more sweets and eight less sweets. How many children are there? * * * How many sweets are there? 2. A customer went to a department store and bought two items (both in whole numbers). When paying, he left out 0% of the unit price of a commodity, and prepared to pay 37 yuan for delivery. The salesman said; "You read the unit price wrong. You should pay 9 1 yuan." Calculate the unit price of these two commodities. 3. A book has three volumes, the first volume is more expensive than the second volume, 0.3 yuan, and the second volume is more expensive than the second volume, 0.6 yuan. One * * of the three volumes is known as 19.5 yuan. Q: How much are the first, second and third volumes? The speed of the ship in still water is 2 1 m per hour. How long does it take for the ship to sail upstream from Port A for 8 hours to reach Port B 144 km, and then return to Port A from Port B? 5. There are 1800 pear trees, apple trees and peach trees, of which the number of pear trees is twice that of apple trees and the number of peach trees is three times that of apple trees. How many apple, pear and peach trees are there? They go home after school. Xiaohong walks 55 meters every minute and gets home in 6 minutes. Xiaoming walks 60 meters every minute and gets home in 8 minutes. Can you figure out how many meters Xiaohong is from a minor celebrity artist? what do you think? 7. On average, the library puts 1 1520 books on 16 shelves, and each shelf has 6 shelves. How many books are there on average on each shelf? 8. At the same time, two warships are conducting relative exercises from two ports 405 nautical miles apart, and one is sailing at a speed of 2 1 nautical mile; The other ship traveled 24 nautical miles per hour and continued to sail after encountering it. Each ship returned immediately after arriving at the port where the other party started, and met for the second time on the way. How long does it take from departure to the second meeting?