Ответ:

  1. а) \(\frac{2}{3}+0,3=\frac{2}{3}+\frac{3}{10}=\frac{20+9}{30}=\frac{29}{30}\);
  2. б) \(\frac{4}{5}-0,44=0,8-0,44=0,36=\frac{9}{25}\);
  3. в) \(\frac{1}{7}:\frac{2}{7}=\frac{1}{7}\cdot\frac{7}{2}=\frac{1}{2}\);
  4. г) \(\frac{3}{8}\cdot3\frac{1}{5}=\frac{3}{8}\cdot\frac{16}{5}=\frac{6}{5}=1\frac{1}{5}\).

Ответ: а) \(\frac{29}{30}\); б) \(\frac{9}{25}\); в) \(\frac{1}{2}\); г) \(\frac{6}{5}\).