[tex]15. \: \frac{3}{14} \times (1 +3 \frac{1}{5} - 4 \frac{1}{5} \times \frac{3}{7} - 1) = \frac{3}{14} \times(3 \frac{1}{5} - \frac{21}{5} \times \frac{3}{7} ) = \frac{3}{14} \times ( 3 \frac{1}{5} - \frac{9}{5} ) = \frac{3}{14} \times ( \frac{16}{5} - \frac{9}{5} ) = \frac{3}{14} \times \frac{7}{5} = \frac{3}{10} [/tex]
[tex]16. \: \frac{2}{3} \times 1 \frac{2}{7} = \frac{2}{3} \times \frac{9}{7} = \frac{6}{7} [/tex]
