6 quarters and 22 dimes.
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1) Gathering the data
d +q = 28
1 dime = $0.10
1 quarter = $0.25
2) So we can write a system of linear equations and then solve:
d+ q = 28
0.1d+0.25q=3.70
d+ q = 28 Multiplying it by -0.1
0.1d+0.25q=3.70
Adding those equations:
-0.1d+ -0.1q = -2.8
0.1d+0.25q=3.70
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0.15q=0.9 Dividing both sides by 0.15
q =6
Plugging into the first equation
d +q =28
d +6 =28 Subtracting from both sides
d = 22