SOLUTION: In a collection of coins there are 7 less dimes than there are quarters. if the value of the collection is $3.85, then how many dimes are there?

Question 838722: In a collection of coins there are 7 less dimes than there are quarters. if the value of the collection is $3.85, then how many dimes are there?
Answer by LinnW(1048) (Show Source): You can put this solution on YOUR website!
d = number of dimes
q = number of quarters
d = q - 7
0.10d + 0.25q = 3.85
substitute (q - 7) for d
0.10(q - 7) + 0.25q = 3.85
0.10q - 0.70 + 0.25q = 3.85
0.35q - 0.70 = 3.85
add 0.70 to each side
0.35q = 4.55
divide each side by 0.35
q = 4.55/0.35
q = 13
d = 13-7 = 6
$0.60 in dimes + $3.25 in quarters is $3.85
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