If There Are Two Coins That Equal 55 Cents and One Is Not a Nickel, What Are the Two Coins?

The only way to solve this puzzle is to make one coin a half-dollar, or 50-cent piece, and the other coin a nickel. The other coins available for circulation in the United States are all too small in denomination for two of them to add up to 55 cents.

The coins currently in circulation in the United States are the penny (one cent), the nickel (five cents), the dime (10 cents), the quarter (25 cents), the half-dollar (50 cents) and the one-dollar coin. While half-dollars are still minted and placed in collectible sets, they are not issued for circulation; however, they occasionally turn up in change drawers and coin jars that people keep at home.