SOLUTION: A dollar was changed into 16 coins consisting of just 5 cent and 10 cent coins. How many coins of each kind were in the change?

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Question 581167: A dollar was changed into 16 coins consisting of just 5 cent and 10 cent coins. How many coins of each kind were in the change?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = number of 10 cent coins
Let +n+ = number of 5 cent coins
given:
(1) +d+%2B+n+=+16+
(2) +10d+%2B+5n+=+100+ ( in cents )
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Multiply both sides of (1) by +5+
and subtract (1) from (2)
(2) +10d+%2B+5n+=+100+
(1) +-5d+-+5n+=+-80+
+5d+=+20+
+d+=+4+
and
(1) +d+%2B+n+=+16+
(1) +4+%2B+n+=+16+
(1) +n+=+12+
The number of 10 cent coins is 4
The number of 5 cent coins is 12