Question

SOS
Даю много балов

Answer 1

Ответ:

$\frac{1}{ \frac{1}{30} + \frac{1}{42} } = \frac{1}{ \frac{7 + 5}{210} } = = \frac{1}{ \frac{12}{210} } = 1 \times \frac{210}{12} = \frac{210}{12} = 17.5$