11) 6 1/5 - 2 4/5 =

11) $$\begin{aligned}6\frac{1}{5} - 2\frac{4}{5} &= 5 + \frac{5}{5} + \frac{1}{5} - 2\frac{4}{5} = 5 + \frac{6}{5} - 2 - \frac{4}{5} = 3\frac{2}{5}\\\\&=\frac{3 \cdot 5 + 2}{5} = \frac{15+2}{5} = \frac{17}{5} = 3\frac{2}{5}\end{aligned}$$

Ответ: 3 2/5