Well, seeing the information above, he used 5/8 of paint to paint the fence and table top. If he only had 1/8 left of the paint, he used 2/8 on the chair.
I found the 5/8 because I needed a common denominator. I multiplied the top and bottom by 2 to get 2/8. 3/8+2/8=5/8, and then I added 2/8 to the 5/8 that then gave me 7/8 of paint used, and 1/8 of paint left.
Hope I helped!