2)3c 3d c-d +d-c

2) $$\frac{3c}{c - d} + \frac{3d}{d - c} = \frac{3c}{c - d} - \frac{3d}{c - d} = \frac{3c - 3d}{c - d} = \frac{3(c - d)}{c - d} = 3.$$

Ответ: $$3$$