The expression is: rt - 2n = y Rearrange it so that only rt is on the left side of the equation: rt = y + 2n Rewrite the left side of the equation: r * t = y + 2n Divide both sides of the equation by r: r * t / r = (y + 2n)/r r can be cancelled out on the left side of the equation: t = (y + 2n)/r
