well you have to leave x by it self so you would subtract z first and move it to the right now you would be left with m=bx now divide by b to leave the x by itself and get m/b=x
z-m=z+bx First, let's subtract z from each side: z-m-z = z+bx-z -m=bx Then, to find x, you divide both sides by b to get the variable x alone on a side, and the others on another side: -m/b = bx/b -m/b = x