1) $$\frac{4mn - m^2}{7} \cdot \frac{14c}{m^4} = \frac{m(4n - m)}{7} \cdot \frac{14c}{m^4} = \frac{14cm(4n-m)}{7m^4} = \frac{2c(4n-m)}{m^3} = \frac{8nc - 2cm}{m^3}$$
Ответ: (8nc-2cm)/m³