Question 157884
{{{P[a]+P[b]=5hours}}} ----------------------> working eqn
Also, {{{P[a]=T[hr]}}}, {{{P[b]=(T-4)[hr]}}}
Substitute in  working eqn:
{{{T+(T-4)=5hours}}}
{{{2T=5+4=9}}} ----> {{{cross(2)T/cross(2)=9/2}}}
{{{T=4.5hours}}} ---------------------------> for {{{Pump[a]}}}
{{{T-4=4.5-4=0.5hour}}} --------------------> for {{{Pump[b]}}}
In doubt? go back working eqn:
{{{4.5hrs+0.5hr=5hours}}}
{{{5hours=5hours}}}
Thank you,
Jojo