Me with 9, 10, 11, 12, 13 & 14

9 cars

13.25$

22.7 miles

It weighs .01 kilograms and 1000 milligrams

4 classes

29,889 Ft 9963 yds

9) 42/5= 8.4 but you can't have part of a car so round up to get 9 cars 
10) 39.75/3= $13.25 per pair
11) 500/22=22.72 repeating, I would say an average of 23 mile per gallon
12) Kilograms- 0.01 and milligrams- 10,000
13) 112/35= 3.2 or 4
14)162 times 210= 34020 and 51 times 81= 4131
34,020-4,121= 29,889 ft and 3,321 yds

I really hope that I helped you!!!

He will need 2,898 pieces of paper