4) 14 6/13 - 12/13 =

4) $$\begin{aligned}14\frac{6}{13} - \frac{12}{13} &= 13 + \frac{13}{13} + \frac{6}{13} - \frac{12}{13} = 13 + \frac{19}{13} - \frac{12}{13} = 13\frac{7}{13}\\\\&=\frac{13 \cdot 13 + 7}{13} = \frac{169+7}{13} = \frac{176}{13} = 13\frac{7}{13}\end{aligned}$$

Ответ: 13 7/13