How many stamps

Question

a manager bought some stamps. She gave 1/3 of them to a cashier and 1/5 of them to her secretary. If the secretary received 40 fewer stamps than the cashier, how many stamps did the cashier receive? 

Answer 1

1/3 - 1/5 = 5/15 - 3/15 = 2/15.

 

Two parts of 15 = 40. This means one part = 20, so 15 parts = 300.

 

1/3 of 300 = 100, so the cashier received 100 stamps.

 

It doesn't ask, but 1/5 of 300 = 60, and 100 - 60 = 40, the difference given.