<PRE><B>Question 252632</B>
This a job / time problem. Here is the formula

J1 / T1 * (together time) + J2 / T2 * (together time) = Total jobs.

Pump 2 does 1 job in x hours. So, J2 / T2 = 1/x.
Pump 1 does 1 job in 4x hours. So, J1 / T1 = 1/4x. 
together time = 3
total jobs  = 1 [1 tank].
{{{(1/4x)*(3) + (1/x)*(3) = 1}}}
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step 1 multiply by 4x.
{{{1*(3) + 1*(3)*(4) = 4x}}}
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step 2 - solve for x.
{{{3 + 12 = 4x}}}
15 = 4X
X = 15/4 = 3.75 hours.
Pump 2 rate = 4/15 hours
pump 1 rate = 1/15 hours.</PRE>