Solve for x when,
18 = 6 (2x - 8)
Divide both sides of the equation by 6 and you have
18/6 = [6 (2x - 8)]/6
3 = 2x - 8
Note that the 6 cancels out each other in the right side of the equation
3 = 2x - 8
Add 8 to both sides of the equation
3 + 8 = 2x -8 + 8
11 = 2x
(Similarly, -8 + 8 equals zero)
11 = 2x
Divide both sides of the equation by 2
5.5 = x