5 dimes
Two quarters is $0.50.
1. 5 dimes = 5 * $0.10 = $0.50
2. 5 dimes + 1 nickel = 5 * $0.10 + $0.05 = $0.55
3. 4 dimes = 4 * $0.10 = $0.40
5. 4 dimes + 1 nickel = 4 * $0.10 + $0.05 = $0.45
The only amount of money that's equal to $0.50 is 1. 5 dimes
