Answer:
Joey has 18 nickles and 27 dimes in his piggy bank.
Explanation:
1 nickle = 5 cents
1 dime = 10 cents
$1 = 100 cents
$3.15 = 135 cents
Let
n represent the number of nickles, n>=0
d represent the number of dimes, d>=0
Joey counted a total of 45 coins that added up to $3.15:
n + d = 45
5n + 10d = 315
n = 18 nickles
d = 27 dimes