SOLUTION: if i have 20 coins only dimes and quarters and have $3.80 how many quters do i have

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Question 373028: if i have 20 coins only dimes and quarters and have $3.80 how many quters do i have
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let d = number of dimes
Let q = number of quarters
given:
(1) d+%2B+q+=+20
(2) 10d+%2B+25q+=+380 (in cents)
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Multiply both sides of (1) by 10
and subtract (1) from (2)
(2) 10d+%2B+25q+=+380
(1) -10d+-+10q+=+-200
15q+=+180
q+=+12
And, from (1),
d+%2B+12+=+20
d+=+8
I have 8 dimes and 12 quarters
check answer:
(2) 10d+%2B+25q+=+380
(2) 10%2A8+%2B+25%2A12+=+380
80+%2B+300+=+380
OK