в) 4/9ab³ ⋅ 3/2ab; г) x²y⁵⋅ (-6xy²);

в) $$\frac{4}{9}ab^3 \cdot \frac{3}{2}ab = \frac{4 \cdot 3}{9 \cdot 2} \cdot (a \cdot a) \cdot (b^3 \cdot b) = \frac{12}{18}a^2b^4 = \frac{2}{3}a^2b^4$$

Ответ: $$\frac{2}{3}a^2b^4$$

г) $$x^2y^5 \cdot (-6xy^2) = -6 \cdot (x^2 \cdot x) \cdot (y^5 \cdot y^2) = -6x^3y^7$$

Ответ: $$-6x^3y^7$$