Try using 2 and 5.. 2x{[(12-3)x3]+(5x6)-8}=98
The function and the first value stated for x are confusing.
Doing some research, I found that the problem is to evaluate the function

for x = - 1 and x 2.
The solution is:
1) For x = - 1

2) For x = 2
Multiply 10.5 and 23.5 to get 246.75. Divide that by 3 and you have your answer, 82.25.
Its the AAS Congruence Theorem. If you account for the vertical angles, the angle marked, and the one side marked it makes AAS. Hope it helped :))