Question

A dealer packages marbles in two different box sizes. One size holds 5 marbles and the other size holds 12 marbles. If the dealer packaged 99 marbles and used more than 10 boxes, how many boxes of each size did he use?

Answer 1

I did trial and error by deducting 12 from 99 until I reached an amount which can be divided by 5.

15 boxes holding 5 marbles and 2 boxes holding 12 marbles.

15 * 5 = 75
 2 * 12 = 24
total of 99 marbles and 17 boxes.