SOLUTION: I would appreciate it very much if I could get help with this problem. A vending machine's coin box contains nickels, dimes, and quarters. The total number of coins in the box is

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Question 625478: I would appreciate it very much if I could get help with this problem.
A vending machine's coin box contains nickels, dimes, and quarters. The total number of coins in the box is 300. the number of dimes is three times the number of nickels and quarters together. If the box ontains $30.05, find the number of nickels, dimes, and quarters thatit contains.

Found 2 solutions by richwmiller, josmiceli:
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
n+d+q=300;
d=3*(n+q);
25q+10d+5n=3005
d = 225, n = 56, q = 19

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
given:
(1) +n+%2B+d+%2B+q+=+300+
(2) +d+=+3%2A%28+n+%2B+q+%29+
(3) +5n+%2B+10d+%2B+25q+=+3005+ ( in cents )
-----------------------==
(2) +d+=+3n+%2B+3q+
Substitute this into (1)
(1) +n+%2B+3n+%2B+3q+%2B+q+=+300+
(1) +4n+%2B+4q+=+300+
(1) +4q+=+300+-+4n+
(1) +q+=+75+-+n+
Substitute this into (3)
(3) +5n+%2B+10d+%2B+25%2A%28+75+-+n+%29+=+3005+
(3) +5n+%2B+10d+%2B+1875+-+25n+=+3005+
(3) +10d+=+20n+%2B+1130+
(3) +d+=+2n+%2B+113+
Substitute this back into (1)
(1) +n+%2B+d+%2B+q+=+300+
(1) +n+%2B+2n+%2B+113+%2B+75+-+n+=+300+
(1) +2n+=+300+-+113+-+75+
(1) +2n+=+112+
(1) +n+=+56+
and, since
(1) +q+=+75+-+n+
(1) +q+=+75+-+56+
(1) +q+=+19+
and
(3) +d+=+2n+%2B+113+
(3) +d+=+2%2A56+%2B+113+
(3) +d+=+225+
There are 56 nickels, 225 dimes, and 19 quarters
check answer:
(3) +5n+%2B+10d+%2B+25q+=+3005+
(3) +5%2A56+%2B+10%2A225+%2B+25%2A19+=+3005+
(3) +280+%2B+2250+%2B+475+=+3005+
(3) +3005+=+3005+
OK- you can check the other 2 equations