$(\frac{16}{27} - \frac{5}{9}) * \frac{3}{10} = \frac{1}{90}$
а) $\frac{16}{27} - \frac{5}{9} = \frac{16 - 5 * 3}{27} = \frac{16 - 15}{27} = \frac{1}{27}$
б) $\frac{1}{27} * \frac{3}{10} = \frac{1 * 3}{27 * 10} = \frac{1 * 1}{9 * 10} = \frac{1}{90}$

$\frac{16}{27} - \frac{5}{9} * \frac{3}{10} = \frac{23}{54}$
а) $\frac{5}{9} * \frac{3}{10} = \frac{5 * 3}{9 * 10} = \frac{1 * 1}{3 * 2} = \frac{1}{6}$
б) $\frac{16}{27} - \frac{1}{6} = \frac{16 * 2 - 1 * 9}{54} = \frac{32 - 9}{54} = \frac{23}{54}$

$(6 - 2\frac{2}{7} * 1\frac{5}{44}) * 2\frac{17}{19} = 10$
а) $2\frac{2}{7} * 1\frac{5}{44} = \frac{16}{7} * \frac{49}{44} = \frac{16 * 49}{7 * 44} = \frac{4 * 7}{1 * 11} = \frac{28}{11} = 2\frac{6}{11}$
б) $6 - 2\frac{6}{11} = 5\frac{11}{11} - 2\frac{6}{11} = 3\frac{5}{11}$
в) $3\frac{5}{11} * 2\frac{17}{19} = \frac{38}{11} * \frac{55}{19} = \frac{38 * 55}{11 * 19} = \frac{2 * 5}{1 * 1} = 10$