$$1\frac{1}{2} = \frac{1*2 + 1}{2} = \frac{3}{2} = 1.5$$
$$1\frac{1}{6} = \frac{1*6 + 1}{6} = \frac{7}{6}$$
$$1.8 - 1.5 = 0.3$$
$$\frac{2}{9} * 0.3 = \frac{2}{9} * \frac{3}{10} = \frac{6}{90} = \frac{1}{15}$$
$$\frac{2}{7} * 0 = 0$$
$$1.2 - 0 = 1.2$$
$$\frac{7}{6} * 1.2 = \frac{7}{6} * \frac{12}{10} = \frac{7 * 2}{10} = \frac{14}{10} = 1.4$$
$$\frac{1}{15} - 1.4 = \frac{1}{15} - \frac{14}{10} = \frac{1}{15} - \frac{7}{5} = \frac{1}{15} - \frac{21}{15} = -\frac{20}{15} = -\frac{4}{3} = -1\frac{1}{3}$$
Ответ: $$-1\frac{1}{3}$$