In this question the main thing that needs to be done is the calculation part. Other than that this problem is a very simple problem.Now
66 2/3% = (200/3)%
Then
(200/3)% of 39 = [200/(3 * 100)] * 39
= (200/300) * 39
= (2/3) * 39
= 2 * 13
= 26
So the answer to the given question is 26. I hope the procedure for doing such problems is clear to you. In future you can do these type of problems on your own without needing the help from any other person.