15) Решите уравнение: \(p+2\frac{1}{5}p+\frac{3}{10}p=1\frac{1}{20}\).

\[\left(1+\frac{11}{5}+\frac{3}{10}\right)p=\frac{21}{20}\]

\[\frac{5}{2}p=\frac{21}{20},\qquad p=\frac{21}{20}\cdot\frac{2}{5}=\frac{21}{50}\]

Ответ: \(p=\frac{21}{50}\).