Sally can paint a room in 9 hour thus her rate is 1/9 rooms per hour

Steve needs 3 hours to paint the same room thus his rate is 1/3 rooms per hour

let x = the hours the need to paint the room together

their together rate is 1/x rooms per hour

now we have:

1/9 + 1/3 = 1/x

by solving we find:

x = 2.25 hr

x = 2 hr 0.25*60 min

x = 2 hr 15 min

click here to see the step by step solution of the equation:

they need 2 hours and 15 min to paint the room together.