数学一元2次方程公式法.帮忙解决一下.谢谢

因为x^2+7xy-60y^2=0.
所以(x-12y)(x+5y)=0
x=12y或x=-5y
x=12y时
x-y/x+y=(12y-y)/(12y+y)=11/13
x=-5y时
x-y/x+y=(-5y-y)/(-5y+y)=3/2
综上所述,x-y/x+y=11/13或3/2