[tex](7 \frac{1}{8} - 4 \frac{7}{8} ) \div ( \frac{5}{7} + 5 \frac{1}{2} \times 1 \frac{1}{7} ) = \\ = ( 6\frac{9}{8} - 4 \frac{7}{8} ) \div ( \frac{5}{7} + \frac{11}{ \not 2{}^{1} } \times \frac{ \not8 {}^{4} }{7} ) = \\ = 2 \frac{2}{8} \div ( \frac{5}{7} + \frac{44}{7} ) = \\ = 2 \frac{2}{8} \div \frac{49}{7} = \\ = 2 \frac{2}{8} \div 7 = \\ = \frac{18}{8} \times \frac{1}{7} = \\ = \frac{18}{56 } = \frac{9}{28} [/tex]
