1. Найдите значение выражения: a) $$3 : 1\frac{1}{2} + 5 : 1\frac{1}{4}$$; б) $$10\frac{2}{3} - 5\frac{1}{3} : 3\frac{1}{5}$$; в) $$4\frac{1}{2} - 5\frac{8}{9} : 10\frac{2}{3}$$

a) $$3 : 1\frac{1}{2} + 5 : 1\frac{1}{4} = 3 : \frac{3}{2} + 5 : \frac{5}{4} = 3 \cdot \frac{2}{3} + 5 \cdot \frac{4}{5} = 2 + 4 = 6$$
б) $$10\frac{2}{3} - 5\frac{1}{3} : 3\frac{1}{5} = \frac{32}{3} - \frac{16}{3} : \frac{16}{5} = \frac{32}{3} - \frac{16}{3} \cdot \frac{5}{16} = \frac{32}{3} - \frac{5}{3} = \frac{27}{3} = 9$$
в) $$4\frac{1}{2} - 5\frac{8}{9} : 10\frac{2}{3} = \frac{9}{2} - \frac{53}{9} : \frac{32}{3} = \frac{9}{2} - \frac{53}{9} \cdot \frac{3}{32} = \frac{9}{2} - \frac{53}{3 \cdot 32} = \frac{9}{2} - \frac{53}{96} = \frac{9 \cdot 48}{2 \cdot 48} - \frac{53}{96} = \frac{432}{96} - \frac{53}{96} = \frac{379}{96} = 3\frac{91}{96}$$