把Y=1,X=7代入原方程组,得
21-m=16
14+n=15
解得m=5,n=1,得
3(x+y)-5(x-y)=16
2(x+y)+(x-y)=15
用换元法解得
x+y=7,x-y=1
再解得x=4,y=3