Question 1007011
Call the numbers of dimes and quarters, d and q.
Thus we have
d + q = 72 and the value equation is
10d + 25q = 1470  (we work in cents)
Now multiply the top equation by 10 and subtract it from the second one...
10d + 25q = 1470
-(10d + 10q = 720)
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15q = 750
Now divide by 15 and get
q = 50 quarters and thus we have
d = 22 dimes