[tex] \frac{2}{5} ( \frac{1}{2} - \frac{7}{8} ) = \frac{2}{5} \times ( \frac{4}{8} - \frac{7}{8} ) = \frac{2}{5} \times (- \frac{ 3}{8} ) = - \frac{6}{40} = - \frac{3}{20} [/tex]
[tex] \frac{25}{14} ( \frac{2}{5} ) {}^{3} + \frac{22}{21} = \frac{25}{14} \times \frac{8}{125} + \frac{22}{21} = \frac{1}{14} \times \frac{8}{5} + \frac{22}{21} = \frac{8}{70} + \frac{22}{21} = \frac{168}{1470} + \frac{1540}{1470} = \frac{1708}{1470} = \frac{122}{105} [/tex]
[tex]( \frac{7}{3} + \frac{1}{6} ) \div \frac{5}{4} = (\frac{14}{6} + \frac{1}{6} ) \times \frac{4}{5} = \frac{15}{6} \times \frac{4}{5} = \frac{3}{6} \times \frac{4}{1} = \frac{12}{6} = \frac{6}{1} = 6[/tex]
