The symbols are rearranged after every "mind reading". They are arranged so that whatever you choose, there is only one possible answer.
Try any combination, you'll always land on same symbol.

AAD: 85.17.97.10:3335 - Training: 81.167.157.3:7766 - GTA U: 85.204.196.64:8901 - Ventrilo: 85.17.146.33:11553

Explain further. I do not understand how it is possible to arrange like that.

The formula doesn't work for all numbers. For example
4: 4+ 0
4-4= 0 (when clicking, the symbol is wrong)

The numbers that always have same symbols:
98, 81, 72, 63, 54, 45, 36, 27, 18, 9,

As an example, here is why 81 will always be the answer:

81 = 98 - (9+8)
81= 97 - (9+7)
81= 96 - (9+6)
81= 95 - (9+5)
etc

81 = z - (x +y)
z=(x*10) + (y)

10x + y -(x +y) = 81
10x - x = 81
x(10 - 1) = 81
9x = 81
x = 81/9 = 9

This only helps so far as when:
x=10 : 10x - x=90 which doesn't work, so it was deleted from magic board.
x=9 : 10x - x=81
x=8 : 10x - x=72
x=7 : 10x - x=63
x=6 : 10x - x=54
x=5 : 10x - x=45
x=4 : 10x - x=36
x=3 : 10x - x=27
x=2 : 10x - x=18
x=1 : 10x - x=9

but if
x=0 : 10x - x=0
all one digit numbers alone don't work in this trick.

and so on.

Eureka

AAD: 85.17.97.10:3335 - Training: 81.167.157.3:7766 - GTA U: 85.204.196.64:8901 - Ventrilo: 85.17.146.33:11553