(x+y)/2=6-(x-y)/33(x+y)=6*6-2(x-y)3x+3y=36-2x+2y5x+y=36 (1) 4(x+y)-5(x-y)=24x+4y-5x+5y=2-x+9y=2 (2)由（1）+（2）*5得5x+y+5(-x+9y)=36+2*546y=46解得y=1x=7
