{3x+4y=19} {x+2y=7}

3x+4y=19 x+2y=7/*(-2) -------------- 3x+4y=19 -2x-4y=-14 ------------- x=5 x=5 4y=19-3x ------------ x=5 4y=19-3*5 ------------- x=5 4y=4 ----------- x=5 y=1

{3x+4y=19} {x+2y=7}/*(-3) {3x+4y=19} {-3x-6y=-21} -2y=-2//:(-2) y=1 x+2*1=7 x+2=7 x=7-2 x=5