ВАРИАНТ 2. 3. Выполните действия: a) \(\frac{5}{6}\) - \(\frac{3}{4}\); б) \(\frac{9}{14}\) + \(\frac{8}{21}\)

a) \(\frac{5}{6}\) - \(\frac{3}{4}\) = \(\frac{5*2}{6*2}\) - \(\frac{3*3}{4*3}\) = \(\frac{10}{12}\) - \(\frac{9}{12}\) = \(\frac{1}{12}\)
б) \(\frac{9}{14}\) + \(\frac{8}{21}\) = \(\frac{9 * 3}{14*3}\) + \(\frac{8*2}{21*2}\) = \(\frac{27}{42}\) + \(\frac{16}{42}\) = \(\frac{43}{42}\)