SOLUTION: Gwen has 65 cents. Using less than or equal to 7 coins, how many different ways can Gwen make 65 cents?

If you don't use any quarters, there is one way, 6 dimes and a nickel.

If you use 1 quarter, you can make the remaining 40 cents 3 ways,
2, 3, or 4 dimes and the rest, if any, in nickels.  

If you use 2 quarters, you can make the remaining 15 cents two ways,
a dime and a nickel, or 3 nickels.

That's 6 ways.

50 cent pieces are not in circulation.  I didn't consider using them.

Edwin