Roberta needs 12 zippers to make 3 of the same backpacks. If Roberta has 48 zippers, how many of those same backpacks can she make?

First, you need to find out how many zippers are used to make one bookbag. To do that, you divide the zippers used to make the 3 backpacks.

12 / 3 = 4

So, 4 zippers are used per bookbag. Then, you divide the number of available zippers by four to find out how many bags she can make.

48 / 4 = 12

Roberta can make 12 bookbags.