Answer:
[tex]\boxed{ \sf\:P=\frac{W\left(R-r\right)}{2R}} [/tex]
Step-by-step explanation:
[tex]\sf\:W = \frac { 2 P R } { R - r }[/tex]
[tex]\sf\:W\left(-r+R\right)=2PR [/tex]
[tex]\sf\:-Wr+WR=2PR [/tex]
[tex]\sf\:2PR=-Wr+WR [/tex]
[tex]\sf\:2RP=RW-rW [/tex]
[tex]\sf\frac{2RP}{2R}=\frac{W\left(R-r\right)}{2R}[/tex]
[tex]\boxed{ \sf\:P=\frac{W\left(R-r\right)}{2R}} [/tex]
Hope it helps ⚜
