Answer:
17%
Explanation:
He completed 1/2 plus 1/3 of the painting.
The total he completed is
1/2 + 1/3 = 3/6 + 2/6 = 5/6
He needs to to 1 - 5/6 = 6/6 - 5/6 = 1/6 of the painting.
100% is the whole. He needs to do 1/6 of 100%.
1/6 * 100% = 100%/6 = 16.666...%
Answer: 17%