If you would like to know in which step did the student first make an error and what is the correct step, you can calculate this using the following steps:
3(2x - 4) = 8 + 2x + 6
6x - 12 = 8 + 2x + 6
6x - 12 = 14 + 2x ... Step 2
6x - 2x = 14 + 12
4x = 26
x = 26/4 = 13/2
The correct result would be Step 2; 6x - 12 = 14 + 2x.