Given that (78)^9 = 6 And (69)^4 = 11 , Can you find out (89)^2 = ?

Question

Given that

(78)^9 = 6
And (69)^4 = 11

Can you find out

(99)^2 =?

(Note: This is Logical not Mathemetical)

Answer 1

7+8-9=6
6+9-4=11
so,
8+9-2=15