math
posted by mary .
if you have 15 coins in a bag and their total amount is $2.70 how many quarters and dimes are in the bag? Use substitution to solve

q+d=15
.25q+.10d=2.70
d=15q
.25q+.10(15q)=2.70
.25q+1.50.10q=2.70
.25q.10q=1.20
.15q=1.20
q=8
q+d=15
8+d=15
d=158
d=7
d stands for dimes
q stands for quarters
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