Question 934291
Understand that the signs for the rate for pipe B and pipe C are opposite, and you want to give a variable to the time for pipe C to empty the tank.


RATES are as TANK per HOURS
Pipe A, {{{1/5}}}
Pipe B, {{{1/(x-2)}}}
Pipe C, {{{-1/x}}}
All pipes open at the same time, {{{1/3}}} tanks per hour.


The rate for all pipes open at the same time is the sum of their individual rates.
...   You see what to do?