Well, you have:
3x + 6 - x = 8 + 3x - 6 ~ First thing is add like terms.
3x - x = 2x
8 - 6 = 2
Now we are left with:
2x + 6 = 3x + 2 ~ Now we need x on one side, so... subtract either 2x or 3x by both sides, in this case I'll subtract 2x by both sides.
6 = x + 2 ~ Now subtract 2 by both sides.
4 = x ~ Or...:
x = 4
That should be the answer, to verify:
3(4) + 6 - 4 = 8 + 3(4) - 6 ~ Multiply.
12 + 6 - 4 = 8 + 12 - 6 ~ Add left terms.
18 - 4 = 20 - 6 ~ Now subtract.
14 = 14 ~ Seems like it adds up.
I hope that helps, have a great rest of your day! ^ ^
{-Ghostgate-}