You have two coins that add up to thirty cents and one is not a quarter. What are the 2 coins?
A quarter and a nickel. Only one isn't a quarter it's a nickel.
Why this works
This riddle plays with the phrasing to create a bit of a trick. The key lies in the statement "one is not a quarter." While it suggests that both coins cannot be quarters, it actually only limits one of them. Thus, you can have a quarter and a nickel: the quarter makes up 25 cents, and the nickel adds 5 cents, totaling 30 cents. The clever twist is that the riddle misleads you into thinking both coins must be something other than a quarter!