Question 211163
 A hose can fill a swimming pool in 6 hours. Another hose needs 3 more hours to fill the pool than the two hoses combined. How long would it take the second hose to fill the pool.
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h1 takes 6 hours, so it fills 1/6 pool per hour.
h2 takes x hours, so it fills 1/x pool per hour.
Together, they do 1/6 + 1/x per hour.
1/6 + 1/x = (x+6)/6x per hour (together), so it takes 6x/(x+6) hours.
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The time the 2nd hose takes, x hours, is 3 hours more than the time together.
x-3 = 6x/(x+6)
(x-3)*(x+6) = 6x
{{{x^2 + 3x - 18 = 6x}}}
{{{x^2 - 3x - 18 = 0}}}
(x-6)*(x+3) = 0
x = 6 hours (Ignore the -3 hours)
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Each hose takes 6 hours.  Together they take 3 hours, so the time for the 2nd hose is 3 hours more than the 3 hours together.