Given the equation
The objective is to solve for x, this means that the x terms must remain alone in one side of the equation. The x term is being multiplied by -2/3, to cancel this multipication you have to divide it by -2/3, and, to keep the equality valid any operation performed in one side of the equation must be performed in the other side of the equation, so you have to divide 4 by -2/3 too: