122. (\(\frac{1}{a} - \frac{1}{b}\)) : \(\frac{b^2 - a^2}{ab^2}\).

122. Упростим выражение:

\((\frac{1}{a} - \frac{1}{b}\)) : \(\frac{b^2 - a^2}{ab^2}\) = \((\frac{b - a}{ab}\)) : \(\frac{b^2 - a^2}{ab^2}\) = \((\frac{b - a}{ab}\)) \cdot \(\frac{ab^2}{b^2 - a^2}\) = \(\frac{(b - a)ab^2}{ab(b^2 - a^2)}\) = \(\frac{b(b - a)}{b^2 - a^2}\) = \(\frac{b(b - a)}{(b - a)(b + a)}\) = \(\frac{b}{b + a}\)

Ответ: \(\frac{b}{b + a}\)