So it took him 4/5 of an hour to paint 1/3 that means there is still 2/3 to go so that means that he will have two times that time to paint the rest of the room 4/5 = ? 1/3 2/3 using cross multiplication (4/5)(2/3) = (1/3) (?) 8/15 = 1/3 ? divide both sides by 1/3 so that will be 8/5 that means it will take 8/5 of an hour to complete the rest