\[\boxed{\text{110.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
Пояснение.
Решение.
\[\textbf{а)}\ \frac{5}{3a} \cdot \frac{2b}{3} = \frac{2 \cdot 2b}{3a \cdot 3} = \frac{10b}{9a}\]
\[\textbf{б)}\ \frac{5a}{8y} \cdot \frac{7}{10} = \frac{5a \cdot 7}{8y \cdot 10} = \frac{7a}{16y}\]
\[\textbf{в)}\ \frac{b^{2}}{10} \cdot \frac{5}{b} = \frac{b^{2} \cdot 5}{10 \cdot b} = \frac{b}{2}\]
\[\textbf{г)}\ \frac{18}{c^{4}} \cdot \frac{c^{3}}{24} = \frac{18 \cdot c^{3}}{c^{4} \cdot 24} = \frac{3}{4c}\]