Question

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Answer 1

Ответ:

$\frac{2}{a- b}$

Объяснение:

$(\frac{b}{a -b}+ \frac{b}{a-b} )* \frac{a-b}{b(a-b)}=\frac{2b}{a-b} * \frac{a-b}{b(a-b)} = 2* \frac{1}{a-b}= \frac{2}{a-b}$