SOLUTION: Rebecca has 45 coins, all nickles and dimes. The total value of the coins is 3.60. How many of each type of coin does Rebecca have?

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Question 538164: Rebecca has 45 coins, all nickles and dimes. The total value of the coins is 3.60. How many of each type of coin does Rebecca 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
given:
(1) +n+%2B+d+=+45+
(2) +5n+%2B+10d+=+360+
-------------------
Multiply both sides of (1) by 5
and subtract (1) from (2)
(2) +5n+%2B+10d+=+360+
(1) +-5n+-+5d+=+-225+
+5d+=+135+
+d+=+27+
and, since
(1) +n+%2B+d+=+45+
(1) +n+%2B+27+=+45+
(1) +n+=+45+-+27+
(1) +n+=+18+
She had 18 nickels and 27 dimes
check:
(2) +5%2A18+%2B+10%2A27+=+360+
(2) +90+%2B+270+=+360+
(2) +360+=+360+
OK