а) $$\frac{2}{3} + \frac{1}{6} = \frac{4}{6} + \frac{1}{6} = \frac{5}{6}$$
б) $$12 - 9\frac{3}{7} = 11\frac{7}{7} - 9\frac{3}{7} = 2\frac{4}{7}$$
в) $$1\frac{1}{3} \cdot 1\frac{1}{2} = \frac{4}{3} \cdot \frac{3}{2} = \frac{4 \cdot 3}{3 \cdot 2} = \frac{12}{6} = 2$$
г) $$36,12 : 12 = 36 \frac{12}{100} : 12 = 36,12 : 12 = 3,01$$
Ответ: а) $$\frac{5}{6}$$; б) $$2\frac{4}{7}$$; в) $$2$$; г) $$3,01$$