Make x the subject of the equation. (x + y)/ 9 = 2x

To make x the subject of the equation, the whole equation has to equal to x only. All x terms have to be moved to one side of the equation and the rest of the terms have to be on the other side of the equation.First, multiply both sides of the equation by the denominator 9: x + y = 18xThen move all the x terms to one side of the equation, and the y terms to the other side of the equation: y = 18x - xSimplify the equation: y = 17xNow, make the equation equal to x only: x = y/17