Question

Marissa has $4.70 in quarters and dimes. If she has 9 more quarters than dimes, how many of each coin does she have?

dimes
quarters

Answer 1

22 dimes

10 quarters

Explanation:

$4.70 = 0.25(q + 9) + 0.1d

4.7 = 0.25q + 0.25(9) + 0.1d

4.7 = 0.25q + 2.25 + 0.1d

2.45 = 0.25q + 0.1d

24.5 = 2.5 + d

22 = d = 22 dimes

$4.70 = 0.25(q + 9) + 0.1(22)

4.70 = 0.25q + 0.25(9) + 2.2

4.70 = 0.25q + 2.25 + 2.2

4.70 = 0.25q + 2.25 + 2.2

4.70 = 0.25q + 4.45

0.25 = 0.25q

1 = q

1 q + 9 q = 10 quarters

Check:

$4.70 = 0.25(q + 9) + 0.1(d)

$4.70 = 0.25(1 + 9) + 0.1(22)

$4.70 = 0.25(10) + 0.1(22)

$4.70 = 2.5 + 2.2

$4.70 = 4.7