2.1. β) 155y: 5y² 100x 25x³

$$ \frac{155y}{100x} : \frac{5y^2}{25x^3} = \frac{155y}{100x} \cdot \frac{25x^3}{5y^2} = \frac{155y \cdot 25x^3}{100x \cdot 5y^2} = \frac{3875x^3y}{500xy^2} = \frac{155x^2}{20y} = \frac{31x^2}{4y} $$

Ответ: $$\frac{31x^2}{4y}$$