Math Story Problem

Well you've got there two basic equations...

10x + 5y + z = 44
x+y+z = 13

It can't be directly solved without a 3rd equation.

So let's look at the minimal number of bills solution,
x=4, y=0, z = 4

That's only 8 bills. While keeping z=4, the most bills we can possible use is:

x=0, y=8, z=4

Which is only 12 bills. Therefore z needs to be > 4. Since z can only be increased in increments of 5 it is a safe bet that z=9.

This leaves a remainder of 35.

x=3, y=1 makes 35.

9+3+1=13. Hooray, the problem is solved.

Now maybe you're teacher will find this and give you an F for cheating...haha

wow thats genius!