Вычислите: a) \frac{3}{4}:\frac{8}{9}; б) 1\frac{7}{8}:0,4; в) 1\frac{1}{3}+\frac{3}{7}:\frac{4}{7}+1\frac{1}{3}.

a) $$\frac{3}{4}:\frac{8}{9}=\frac{3}{4} \cdot \frac{9}{8}=\frac{27}{32}$$

б) $$1\frac{7}{8}:0,4 = \frac{15}{8} : \frac{4}{10} = \frac{15}{8} \cdot \frac{10}{4} = \frac{150}{32} = \frac{75}{16} = 4\frac{11}{16}$$

в) $$1\frac{1}{3}+\frac{3}{7}:\frac{4}{7}+1\frac{1}{3}=\frac{4}{3}+\frac{3}{7} \cdot \frac{7}{4}+\frac{4}{3}=\frac{4}{3}+\frac{3}{4}+ \frac{4}{3}=\frac{16}{12}+\frac{9}{12}+ \frac{16}{12}=\frac{41}{12}=3\frac{5}{12}$$

Ответ: a) $$\frac{27}{32}$$; б) $$4\frac{11}{16}$$; в) $$3\frac{5}{12}$$.