5.539 Найдите значение выражения: а) 6/13 * 39/2; б) 21/11 * 22/3; в) (3/10 + 1/2) * 3/2

а) \(\frac{6}{13} \cdot \frac{39}{2}\) = \(\frac{6 \cdot 39}{13 \cdot 2}\) = \(\frac{6 \cdot 3 \cdot 13}{13 \cdot 2}\) = \(\frac{6 \cdot 3}{2}\) = \(\frac{18}{2}\) = 9 б) \(\frac{21}{11} \cdot \frac{22}{3}\) = \(\frac{21 \cdot 22}{11 \cdot 3}\) = \(\frac{7 \cdot 3 \cdot 2 \cdot 11}{11 \cdot 3}\) = \(7 \cdot 2\) = 14 в) (\(\frac{3}{10} + \frac{1}{2}\)) * \(\frac{3}{2}\) = (\(\frac{3}{10} + \frac{5}{10}\)) * \(\frac{3}{2}\) = \(\frac{8}{10}\) * \(\frac{3}{2}\) = \(\frac{4}{5}\) * \(\frac{3}{2}\) = \(\frac{12}{10}\) = \(\frac{6}{5}\) = 1.2