The motivation of this question is to look if there is such solution in rational number to the  identity which mentioned [here], I have done  many attempts using Wolfram Alpha to find such pairs of rationals $(x,y,z)$ for which  $\frac{x}{y+z}+\frac{y}{x+z}+\frac{z}{y+x}=1$ but I failed even I believed that there are no such solutions? 



[here]:
https://math.stackexchange.com/q/3654326