Л) $$4\frac{15}{49}-2\frac{3}{14}$$

Л) $$4\frac{15}{49}-2\frac{3}{14} = \frac{4 \cdot 49 + 15}{49} - \frac{2 \cdot 14 + 3}{14} = \frac{196+15}{49} - \frac{28+3}{14} = \frac{211}{49} - \frac{31}{14} = \frac{211 \cdot 2}{49 \cdot 2} - \frac{31 \cdot 7}{14 \cdot 7} = \frac{422}{98} - \frac{217}{98} = \frac{422-217}{98} = \frac{205}{98} = 2\frac{9}{98}$$