Question 981179
Do what each can do in an hour.

(1/7) for painter A.

(1/7) + (1/x)=(1/5) , which means in 1 hour, they paint 1/5 of the room

common denominator is 35x
5x+35=7x
2x=35
x=17.5 hours for painter B.

Check
(1/7) + (1/17.5)=(17.5 +7)/122.5 = 24.5/122.5