2(x+y)+3(x-y)=2分之(-9)即10x-2y=-9(1)
4(x+y)-5(x-y)=2即-x+9y=2即-10x+90y=20(2)
(1)+(2)得88y=11,解得y=1/8
代入得x=-7/8
即方程组解为x=-7/8,y=1/8