Question 1207767
5 hp pump does one job in 5 hour.
speed, {{{1/5}}}


2 hp pump does one job in 8 hours
speed, {{{1/8}}}


Both together for 2 hours and then only the 5 hp pump for unknown time x.  One job to complete.


{{{2(1/5+1/8)+(1/5)(x)=1}}}----------a good starting equation.

Multiply both sides by 40, simplify, and solve for x.