SOLUTION: OK, I think this would be under finance,...here's the problem that I can't remember the formula for....the answer is 8 dimes and 4 nickles, but what is the formula to find? Jed

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Question 258519: OK, I think this would be under finance,...here's the problem that I can't remember the formula for....the answer is 8 dimes and 4 nickles, but what is the formula to find?
Jed has a pocket full of nickles and dimes that equal one dollar. He has twice as many dimes as nickles. How many of each coin does he have?

Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
First we start with the value of coins equation:
(i) 5N + 10D = 100
Second, we have the number of coins equation:
(ii) D = 2N
By substitution, we get
(iii) 5N + 10(2N) = 100
solving for N, we get
25N = 100
N = 4
This means that D =8.