原式={x(x-2)+2(x-2)-x(x+1)}/x(x-2) ÷ (x+4)/(x^2-2x)
=(x^2-2x+2x-4-x^2-x)/(x^2-2x) ÷ (x+4)/(x^2-2x)
=(-4-x)/(x+4)
=-1