First you distribute the six to both, the 2x and the -8
18=6*2x+6*-8
= 18=12x+(-48)
Now to solve you use inverse operation of addition to be able to isolate x.
18+48=12x+(-48)+48
66=12x
And now you divide by 12 on both sides so you can get the value of x.
5.5=x
X=5.5 or X=11/2
