$=\frac{\mathrm{R}\left[1+\frac{\mathrm{S}}{\mathrm{R}}\right]}{\mathrm{P}\left[1+\frac{\mathrm{Q}}{\mathrm{P}}\right]}$       ........$(A)$

Also $\frac{\mathrm{P}}{\mathrm{R}}=\frac{\mathrm{Q}}{\mathrm{S}} \Rightarrow \frac{\mathrm{S}}{\mathrm{R}}=\frac{\mathrm{Q}}{\mathrm{P}}$            ...........$(B)$

from  $(A)$ and $(B)$

$\frac{\text { Power in }(\mathrm{P}+\mathrm{Q})}{\text { Power in }(\mathrm{R}+\mathrm{J})}=\frac{\mathrm{R}}{\mathrm{P}}$