a student makes a$8.75 purchase at the bookstore with a $20.00 bill. The store has no bills and gives the change in guarters and fifty-cent pieces. there are 30 coins in all. how many of each kind are there? (trying to find the euqation to this problem it has me stumped). I just don't get it

Question

whpalmer4 · Answer

The amount to be given in change is $20 - $8.75 = $11.75.

There are 30 coins.  Let Q be the number of quarters, and F be the number of fifty-cent pieces.

We know two things:

25Q + 50F = 1175 (we'll do it in cents to be free of decimals)
Q + F = 30

Solve by substitution or elimination.

whpalmer4 · Answer

I hope the student has strong pockets :-)