Problem Solving (PS) | A certain liquid passes through a drain at a rate of w/20 gallons ever

In every rate question, it's appropriate to first create the equilibrium of time -- all represent in the hour, minute, second and so forth. Then try to find the rate of this particular time:
w/60 gallon in x/60 minute or 60w/20x gallon per minute.
y:60w/20x or y:3w/x, which equals to xy/3w.

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