4. Найдите значение выражения: a) \frac{2,8}{16,8}; б) \frac{1,21}{2\frac{4}{11}}; в) \frac{1\frac{2}{3}}{\frac{3}{8}}.

Решение:

a) $$ \frac{2,8}{16,8} = \frac{28}{168} = \frac{1}{6} $$

б) $$ \frac{1,21}{2\frac{4}{11}} = \frac{1,21}{\frac{26}{11}} = \frac{1,21 \cdot 11}{26} = \frac{13,31}{26} = \frac{1331}{2600} = 0,512 $$

в) $$ \frac{1\frac{2}{3}}{\frac{3}{8}} = \frac{\frac{5}{3}}{\frac{3}{8}} = \frac{5}{3} \cdot \frac{8}{3} = \frac{5 \cdot 8}{3 \cdot 3} = \frac{40}{9} = 4\frac{4}{9} $$

Ответ: a) $$\frac{1}{6}$$, б) $$0,512$$, в) $$4\frac{4}{9}$$