2x-y=5 =2x-5=y3x+4(2x-5)=23x+8x-20 =2 11x =22 x=112*11-y=522 =5+y y=17
(1)x4+(2): 11x=22 x=2 代入（1）y=-1
x=2，y=-1
x=2 y=-1
