o: \(=\dfrac{3}{4}\cdot\left[\dfrac{1}{5}-\dfrac{4}{7}-\dfrac{3}{5}\cdot\dfrac{-5}{7}\right]=\dfrac{3}{4}\cdot\left(\dfrac{1}{5}-\dfrac{4}{7}+\dfrac{3}{7}\right)\)
\(=\dfrac{3}{4}\cdot\left(\dfrac{1}{5}-\dfrac{1}{7}\right)=\dfrac{3}{4}\cdot\dfrac{2}{35}=\dfrac{3}{70}\)
p: \(=\left[\left(\dfrac{1}{9}\cdot\dfrac{27}{8}\right)\cdot3\right]\cdot\dfrac{-128}{81}=\dfrac{9}{8}\cdot\dfrac{-128}{81}=\dfrac{-16}{9}\)