The price of 2 postcards is $1. Any combination of coins that adds to $1 will work here. Remember, a penny is worth 0.01, a nickel is worth 0.05, a dime is worth 0.10, and a quarter is worth 0.25.
Adding 2 dimes, 1 nickel, and 3 quarters would be 2(0.10)+1(0.05)+3(0.25)=1.
