Algebraic solution to a coin problem.

Astronomy

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Jan 8, 2012
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Susan has 8 coins that equal 43 cents. What are the 8 coins?
I know the answer is 3 dimes, 2 nickels, and 3 pennies just by
thinking about it. But how can this answer be arrived at using
an algebraic formula?

For example I started by:

p = pennies
n = nickels
d = dimes
q = quarters

p = 1
n = 5p
d = 10p
q = 25p

ap + bn + cd + dq = 43
a + 5b + 10c + 25d = 43
a + b + c + d = 8

a + b + c + d = 3 +2 + 3 + 0 = 8 BUT HOW????

That's as far as I got.
 
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