Question

A man has 14 coins in his pocket, all of which are dimes and quarters. if the total value of his change is $1.70, how many dimes and how many quarters does he have?

Answer 1

d + q = 14....d = 14 - q
0.10d + 0.25q = 1.70

0.10(14 - q) + 0.25q = 1.70
1.40 - 0.10q + 0.25q = 1.70
-0.10q + 0.25q = 1.70 - 1.40
0.15q = 0.30
q = 0.30 / 0.15
q = 2 <=== 2 quarters

d + q = 14
d + 2 = 14
d = 14 - 2
d = 12 <=== 12 dimes