Question 1010820
The rates of the different pumps are given as one unit of capacity in some amounts of time.
The pumps work to remove water from ONE tank.


<pre>
PUMP         RATE(TANKS PER HOUR)
A            1/2
B            1/2
C            1/4
</pre>

The flow rate for the three pumps working at the same time is the sum of their individual rates.


Their combined rate, tanks-worth per hour, {{{1/2+1/2+1/4=highlight(1&1/4)}}}.
This means, that quantity of TANKS, done in 1 HOUR.
YOU want what is amount of time  in order to empty ONE tank.



Reciprocal of  {{{1&1/4}}}.