Question

Emily has a piggy bank that contains 30 coins in dimes and nickels. Their combined value is $2.10. How many coins of each kind are there?

Answer 1

Explanation:

Though we can divide this second equation by five and combine, let's multiply the first equation by five and subtract it from the second...

10d + 5n = 210

-(5d + 5n = 150)

and we get

5d = 60

d = 12 dimes

n = 30-12 = 18 nickels