SOLUTION: Andrew has a change jar that contains only dimes and quarters. He has 73 coins which add up to a total of $13.75. How many of each type of coin does he have? Andrew has dimes

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Question 1176736: Andrew has a change jar that contains only dimes and quarters. He has 73 coins which add up to a total of $13.75. How many of each type of coin does he have?
Andrew has
dimes?
Andrew has
quarters?
Answer by MathLover1(20850) About Me  (Show Source):
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let dimes be d and quarters q
if he has 73 coins altogether, we have
d%2Bq=73
d=73-q....eq.1
1d=$0.10
1q=$0.25
if he has $13.75, then
0.10d%2B0.25q=13.75.....substitute d from eq.1
7.3-0.10q%2B0.25q=13.75
0.15q=13.75-7.3
0.15q=6.45...both sides multiply by 100 to get rid of decimals
15q=645
q=645%2F15
q=43
go to eq.1
d=73-q....eq.1, substitute q
d=73-43
d=30
Andrew has
30 dimes
Andrew has
43 quarters