SOLUTION: In a water refilling station, the time that a pipe takes to fill a tank is 10 minutes more than the time that another pipe takes to fill the same tank. If the two pipes are opened

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Question 1088081: In a water refilling station, the time that a pipe takes to fill a tank is 10 minutes more than the time that another pipe takes to fill the same tank. If the two pipes are opened at the same time, they can fill the tank in 12 minutes. How many minutes does each pipe take to fill the tank?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
x, time for pipe
x+10, time for the first pipe

1%2Fx%2B1%2F%28x%2B10%29=1%2F12
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12x%28x%2B10%29%281%2Fx%2B1%2F%28x%2B10%29%29=12x%28x%2B10%29%281%2F12%29
12%28x%2B10%29%2B12x=x%28x%2B10%29
12x%2B120%2B12x=x%5E2%2B10x
24x%2B120=x%5E2%2B10x

x%5E2-14x-120=0
-
discriminant, 196%2B4%2A120=196%2B480=676=26%5E2;
x=%2814%2B-+26%29%2F2, but only the PLUS form will work.
x=20

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first pipe alone, 20 minutes
second pipe alone, 30 minutes
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