What digit will be in triangle of forth square ?

Question

Answer 1

Sum of digits in every square is 22.
Like :
5+5+6+6=22
7+2+9+4=22
11+6+2+3=22
S0 in fourth square required digit is 9.

Answer 2

9 is the answer

Answer 3

The answes is 9

Answer 4

nine because all others add to 22