f(x)+f(m-x)=2x/(x+2)+2(m-x)/(m-x+2)
=(2mx-2x^2+4x+2mx-2x^2+4m-4x)/(x+2)(m-x+2)
=(-4x^2+4mx+4m)/(x+2)(m-x+2)
=-2
(x+2)(m-x+2)=-x^2+mx+m
m=-4
f(x)+f(m-x)=2x/(x+2)+2(m-x)/(m-x+2)
=(2mx-2x^2+4x+2mx-2x^2+4m-4x)/(x+2)(m-x+2)
=(-4x^2+4mx+4m)/(x+2)(m-x+2)
=-2
(x+2)(m-x+2)=-x^2+mx+m
m=-4