3x - 8 =

multiply both side of the equation by 2
2(3x - 8) = 8x + 4
distribute the 2 to the whole parentheses
2 × 3x = 6x
2 × -8 = -16
6x - 16 = 8x + 4
subtract 4 on each side of the equation
6x - 20 = 8x
subtract 6x on both side of the equation
-20 = 2x
divide both side of the equation by 2
-10 = x
There you go! I really hope this helped, if there's anything just let me know! :)