Luke has 15 coins. He has only nickels and dimes. If the total value of the coins is $1.20, how many nickels does he have?

Write and solve using a system of equations.

The answer is 24. Because if you decide without the decimal then you get 24

He has 6 nickels and 9 dimes.

You can use the equations and suppose x = nickels and y = dimes:

x + y = 15

0.05x + 0.1y = 1.20

You can check if it is correct by substituting x for 6 and y for 9 in both.

(6) + (9) = 15

6 + 9 = 15

15 = 15

0.05 (6) + 0.1 (9) = 1.20

0.3 + 0.9 = 1.20

1.20 = 1.20

Therefore, he has 6 nickels.