Question 794728
Gas fuelled water pump takes 28 minutes
Electric pump takes 21 minutes
Gas pump takes 1/28 job/min
Electric pump takes 1/21 job/min
Together rate = 1/x job/min
1/28 + 1/21 = 1/x
Common denominator = 588x
21x + 28x = 588
49x = 588
x = 12
So together both pumps will
fill the tank in 12 minutes.
Hope this helps.
:-)