Tennis balls cost $7 for a can of 3. Steve gives the cashier $40 t to balls and receives $12 in change. How many tennis ball did Steve buy?

If you subtract 12 from 40, you get 40 - 12 = 28. So, Steve spent $28. Then, you divide 28 by 7. When you do 28/7 you get 4. This means that Steve bought 4 cans of tennis balls. Then, to find the total number of tennis balls purchased, you must multiply the number of cans purchased (4) by the number of balls in each can (3). So, when you do 4 x 3 you get 12. This mean that Steve bought a total of 12 tennis balls.

First, do 40 - 12 = 28 (Subtract the change), then do 28 / 7 to get 4, so then we do the cans times 3 to see how many individual balls he has, which would be 12