SOLUTION: Your piggy bank has a total of 40 coins in it. Some are dimes and some are nickles. If you have a total of $3.50, how many dimes do you have?

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Question 322815: Your piggy bank has a total of 40 coins in it. Some are dimes and some are nickles. If you have a total of $3.50, how many dimes do you have?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let d = number of dimes
Let n = number of nickels
given:
(1) d+%2B+n+=+40
(2) 10d+%2B+5n+=+350 (in cents)
Multiply both sides of (1) by 5 and
subtract (1) from (2)
(2) 10d+%2B+5n+=+350
(1) -5d+-+5n+=+-200
5d+=+150
d+=+30
and
30+%2B+n+=+40
n+=+10
There are 30 dimes and 10 nickels