posted by Willow on .
Christie makes a $9.25 purchase at the bookstore with a $20.00 bill. The store has not bills and gives her change in quarters and 50-cent pieces. There are 30 coins in all. How many of each kind are there?
Are these the correct equations?
x + y = 30
.25x + .5y = 10.75 (that's 20 - 9.25)
looks good so far.
after you solve it, see if your values satisfy the conditions stated in your problem.