Question 253212
This is a job / time question. Here are the things we need:
J1 = job of inlet pipe
J2 = job of drain pipe
T1 = time of inlet pipe
T1 = time of drain pipe
x = time together
Tj = total number of tanks.
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The basic formula is
(i) (J1/T1)*(x) + (J2/T1)*(x) = Tj
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From this we can fill in some information:
-(1/30)*(x) + (1/45)*(x) = 1.
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Solving, we get:
-3x + 2x = 90, which means x = -90
Since x will be negative, there is no solution based on the information given. If the 30 and 45 were reversed, then we would  get an answer.