Question 663851
This is a classic type of problem. The way I do these is as follows:
Sally can paint {1/5) of the room in an hour. Steve can paint 1/8 of the room an hour.
Together they can paint {{{1/5 + 1/8}}} room per hour
{{{1/5 + 1/8 = 8/40 + 5/40 = 13/40}}} room/hour
So how long to paint the whole room?

{{{(13/40)*(numberOfHours) = 1}}}
{{{numberOfHours = 40/13 = 3.077}}} hours. About 3 hours and 5 minutes to paint the room together.