Algebra: A Combined Approach (4th Edition)

4x + y = -13 firat equation 12 x +3y =- 39 multiply by 3 6x - 3y = -15 _______________ 18 x = - 54 add the equations to eleminate y x =- 3 divide both sides by 18 let x = - 3 in first equation $4\times(-3)$ + y = -13 - 12 + y = -13 y = -13 +12 y = -1