Question

A student solved this problem by working backwards.

Joani has some stuffed animals. She has 2 times as many as Lily. Lily has 6 stuffed animals. Joanie gave 2 away and bought 4 more. How many stuffed animals does Joani have now?

Students's solution: Lily has 6 stuffed animals, so Joani had 6 × 2 to begin with. So Joani had 12 stuffed animals. She gave away 2, so 12 – 2 = 10. She bought 4, so 10 + 4 = 14. So Joani has 14 stuffed animals.

Here is another problem that can also be solved by working backwards.

Wyatt has 3 times as many baseballs as golf balls. He has 5 fewer tennis balls than baseballs. Wyatt has 4 golf balls.

How many tennis balls does Wyatt have?


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Answer 1

The first one Joanne has 14 stuffed animals because 6 times 2 is 12. The subtract 12 from 2 and get 10 and she bought 4 more which would be 14.

Answer 2

Wyatt has 7 tennis balls b/c 4 ("4 golf balls") times 3 ("3 times as many baseballs") equals 12 and then you subtract 5 ("5 fewer tennis balls") and you get 7.