1998 IMO Shortlist Problems/A3

Let be positive real numbers such that . Prove that $\frac{x^3}{(1+y)(1+z)}+\frac{y^3}{(1+x)(1+z)}+\fra{z^3}{(1+x)(1+y)}\geq \frac{3}{4}$ (Error compiling LaTeX. Unknown error_msg)