1/3 and 2/5 --> what we need is a least common denominator (1/3)x5 (2/5)x3 5/15 and 6/15 so he needs to paint his room two more times which will make the 5/15 become 15/15 you start with 5/15 and you need to add "5/15" two more times which will make 15/15 so you do that to 6/15 6/15+6/15+6/15=18/15=1 3/15 or 1 1/5 cans of paint ANSWER