$(6,8 - 5\frac{5}{9}) : (2\frac{13}{30} - 2\frac{1}{12}) * 3,6 = (6\frac{4}{5} - 5\frac{5}{9}) : (2\frac{26}{60} - 2\frac{5}{60}) * \frac{18}{5} = (6\frac{36}{45} - 5\frac{25}{45}) : \frac{7}{20} * \frac{18}{5} = \frac{56}{45} : \frac{7}{20} * \frac{18}{5} = \frac{56}{45} * \frac{20}{7} * \frac{18}{5} = \frac{8}{5} * \frac{4}{1} * \frac{2}{1} = \frac{64}{5} = 12\frac{4}{5}$