Math puzzle, need help?

Question

http://www.myfilehut.com/userfiles/209012/puzzle.jpg

This is the URL to the problem I have, I cannot find the answer and need help.

Answer 1

Replace the corners with the sum of the odd digits:

Your square looks like this now:

12 - 21 - 9

16 ? 10

4 5 1


Notice, add the corners and you get the middle. Add 9 and 4 and the question mark becomes 13.

Answer 2

the problem is i can't access that site..

im in my office.. =(

too bad i can't help at all...