Question

Selma's class is making care packages to give to victims of a natural disaster. Selma packs one box in 5 minutes and has already packed 12 boxes. Her friend Trudy packs one box in 7 minutes and has already packed 18 boxes. How many more minutes does each need to work in order to have backed the same number of boxes?

Answer 1

Every 35 minutes Selma packs 7 boxes, while Trudy packs 5 boxes.

Thus every 35 minutes Selma decreases the difference between them in 2 boxes.

Since the original difference was 6 boxes, Selma needs 3 times 35 minutes, or 105 minutes, in all, to catch Trudy.

Answer- 105 minutes, or 1 hour and 45 minutes.