If you expand the left hand sign, the equation becomes
[tex] 3x-6 = 3x-2 [/tex]
This means that the term [tex] 3x [/tex] cancels out, since it appears in both sides. So, we're left with
[tex] -6=-2 [/tex]
which is clearly false, i.e. it leads to an impossible equation, which thus have no solutions.
