I think I know it.
First, you need to distribute the coefficients to the items in the ()'s
30-10x+2x-4=12x-4
Then you need to carry over the x's on one of the sides.
-10x+10x=0x
12x+10x=22x
2x-2x=0x
22x-2x=20x
30-4=20x-4
Then, move over the -4 to the other side. The point of this is to have all numbers on one side and all variables on the other side, while keeping the equation equal.
-4+4=0
You may want to do 30-4 first before doing the next step.
26+4=30
30=20x
Finally, divide 30 by 20
30/20=1.5
x=1.5
Therefore, X equals 1.5
I spent about 10 minutes on this answer. I really hope this helps!