Of course, you haven't given the equation, but the rule is with equations that if a multiplication factor on one side of an equation appears on the other side you can divide both sides of the equation by that factor, provided it isn't zero. Similarly for divide, when you would multiply by the factor.
If an addition or subtraction factor appears on each side of an equation you can subtract or add that factor from both sides of the equation. If the factor is called x or some multiple of x (e.g., 4x) or some other variable name the same rule applies. But you do need to make sure that the suspected factor isn't bound up in a relationship with another factor. So if your equation looks like x times something = x times something else, then dividing by x on both sides you're left with something=something else. Similarly if x were dividing, when you would multiply to cancel the common factor.
If your equation looks like something plus x or x plus something = x plus something else or something else plus x, then subtracting x from both sides leaves something = something else. Similarly for minus, you simply add x to both sides. Does this help?