THREE COINS

Credit: NPR Weekend Edition Sunday Puzzle

July 3, 2005

Presented by Will Shortz

Puzzle by Eric Friedman

[Note from JA: I do not know how this problem was solved, as no explanation was given. This puzzle was used in the U.S. Puzzle Championship in 2005. There are two possible answers.]

A certain country mints coins in only three denominations. Each denomination is an integral number (1, 3, 4, etc.) The amounts 20, 23, and 29 can be made exactly by using three coins. What are the denominations of the coins?

**Answers:**

**6, 7, 11 or**

**5, 9, 10**