2*（2x+y）=1*2
4x+2y=2 (1)
5x+2y=7 (2)
(2)-(1):
5x+2y-4x-2y=7-2
得x=5
把x=5代入2x+y=1
2*5+y=1;
y=-9
所以得：x=5;y=-9