Andrew has 12 coins, all dimes and nickels, and they add up to $1.00. How many nickels does he have?

Answer 1

d = number of dimes
n = number of nickels

d + n = 10
.10d + .05n = 1.00

Solve the first equation for n or d and substitute it into the second equation.

Answer 2

7 quarters 3 dimes and 3 nickels