Question 443652
Filling the pool is 1 job

x hours hose 1
so hose 1 will do 1/x of the job in 1 hour
..
Similarly hose 2 will do 1/y of the jon in 1 hour.

..
together they will do 1/x + 1/y  of the job in 1 hour
..
= (x+y)/xy 
..
to do the complete job they together will take
xy/(x+y) hours