$$ \frac{p-q}{p} \cdot (\frac{p}{p-q} + \frac{p}{q}) = \frac{p-q}{p} \cdot (\frac{pq + p(p-q)}{(p-q)q}) = \frac{p-q}{p} \cdot (\frac{pq+p^2-pq}{(p-q)q}) = \frac{p-q}{p} \cdot \frac{p^2}{(p-q)q} = \frac{(p-q)p^2}{p(p-q)q} = \frac{p}{q} $$
Ответ: $$ \frac{p}{q} $$