б) 5x ⋅ 2y² - 5x ⋅ 3xy - x²y + 6xy².

б) $$5x \cdot 2y^2 - 5x \cdot 3xy - x^2y + 6xy^2 = 10xy^2 - 15x^2y - x^2y + 6xy^2 = (10xy^2 + 6xy^2) + (-15x^2y - x^2y) = 16xy^2 - 16x^2y$$.

Ответ: $$16xy^2 - 16x^2y$$