[tex]W=GMm(\frac{1}{r}-\frac{1}{R}) \\\\W=\frac{GMm}{r}-\frac{GMm}{R}\\\\\frac{GMm}{r}=W+\frac{GMm}{R}\\\\\frac{GMm}{r}=\frac{WR+GMm}{R}\\\\r(WR+GMm)=GMmR\ \ \ |:(WR+GMm)\\\\r=\frac{GMmR}{WR+GMm}[/tex]
