Question

You have 59 total coins for a total of 12.05. You only have quarters and dimes. How many of each coin do you have?

Answer 1

Ok, let's settle this with a simultaneous equation...

0.25 * X + 0.10 * Y = 12.05

X + Y = 59

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This means that:

X = 59 - Y

Which means that:

0.25 * (59 - Y) + 0.10 * Y = 12.05

0.25 * 59 - 0.25 * Y + 0.10 * Y = 12.05

Y (0.10 - 0.25) = 12.05 - 0.25 * 59

-0.15 * Y = -2.7

Y = (-2.7)/(-0.15)

Y = 18

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X + Y = 59

Therefore:

X + 18 = 59

X = 59 - 18

X = 41

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There are 41 quarters and 18 dimes.