algebra
posted by Willow .
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 50cent 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)
Thanks! :)

looks good so far.
after you solve it, see if your values satisfy the conditions stated in your problem.