X + 3 = 8
x = 8 - 3
x = 5 <=
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.
If she used all of her yarn, she'd have 24 pieces. If she wanted 1.25 left, she'd have ten less because 24 • .125 = 8, and 1/4 of eight = 2, and 2 + 8 = 10.
So she'd have 14 pieces.
