Question

Roberto has $22. He buys some notebooks costing $2 each and some binders costing $5 each. If Roberto spends all $22 how many of each does he buy?

Answer 1

Hmm it doesn't seem like there is enough information here. Although, since it says he purchased "some" binders and "some notebooks I guess we can assume he bought at least 2 of each.

So try to think of combinations that would use up all 22 dollars with no money left over. :D

Answer 2

For example if he bought 2 binders, that would cost $10. How many notebooks could he buy with the left over money?

Answer 3

From Mathematica:
Maximize[{ 2n+5b, 2n+5b=22, n>0, b>0}, { n, b }, Integers]
{22,{n->1,b->4}}