SOLUTION: I have 42 coins with a total of $13.50.Some of my coins are 5-cent coins, and I have four times as many 50-cent coins and the rest are 10-cent coins. How many 10-cent coins have I

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Question 847472: I have 42 coins with a total of $13.50.Some of my coins are 5-cent coins, and I have four times as many 50-cent coins and the rest are 10-cent coins. How many 10-cent coins have I got?
ps can you get back to me as quick as possible
Answer by swincher4391(1107) About Me  (Show Source):
You can put this solution on YOUR website!
Let n = # of nickels
Let 4n = # of 50-cent coins
Let 42-5n = # of ten-cent coins

.05 * n + .50*4n + .10(42-5n) = 13.50
.05n + 2n + .42 - .5n = 13.50
1.55n = 9.3
n = 6
42-5n represents ten-cent coins 42-5(6) = 12 ten-cent coins <--- ANSWER
Verify:
6 nickles
24 50-cent coins
12 dimes
-----------
42 coins
6*.05 + 24*.50 + 12*.10 = .30 + 12 + 1.20 = 13.50