Got a math test tmr HELP!!

I don't have any social media, and i don't any site that can help me in math. So it would be nice if you all coud recommend me a site or app that could help me in this question.
If anyone is good at math I'll appreciate if you could help me in this question:
f(x)=x/(e^x +1)
Slove :
f(x)=f(m)