14) $$\frac{12a+5b}{3b} - \frac{2a-b}{3b} = \frac{12a+5b - (2a-b)}{3b} = \frac{12a+5b - 2a + b}{3b} = \frac{10a + 6b}{3b}$$
Ответ: $$\frac{10a+6b}{3b}$$