SOLUTION: Please help ! In Peter's piggy bank, there are 6 times as many dimes as quarters and 8 more nickels than quarters. If Peter has $9.4 in his bank, how many quarters does he have?

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Question 951383: Please help !
In Peter's piggy bank, there are 6 times as many dimes as quarters and 8 more nickels than quarters. If Peter has $9.4 in his bank, how many quarters does he have?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +n+ = number of nickels
Let +d+ = number of dimes
Let +q+ = number of quarters
-----------------------------
(1) +d+=+6q+
(2) +n+=+q+%2B+8+
(3) +5n+%2B+10d+%2B+25q+=+940+ ( in cents )
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Substitute (1) and (2) into (3)
(3) +5%2A%28+q+%2B+8+%29+%2B+10%2A6q+%2B+25q+=+940+
(3) +5q+%2B+40+%2B+60q+%2B+25q+=+940+
(3) +90q+=+900+
(3) +q+=+10+
---------------
(1) +d+=+6q+
(1) +d+=+6%2A10+
(1) +d+=+60+
---------------
(2) +n+=+q+%2B+8+
(2) +n+=+10+%2B+8+
(2) +n+=+18+
----------------
There are:
18 nickels
60 dimes
10 quarters
------------
check:
(3) +5n+%2B+10d+%2B+25q+=+940+
(3) +5%2A18+%2B+10%2A60+%2B+25%2A10+=+940+
(3) +90+%2B+600+%2B+250+=+940+
(3) +940+=+940+
OK