14) $$(50xy^4) : (10xy) = \frac{50xy^4}{10xy} = \frac{50}{10} \cdot \frac{x}{x} \cdot \frac{y^4}{y} = 5 \cdot 1 \cdot y^{4-1} = 5y^3$$
Ответ: $$5y^3$$