Решение:

a) $$\frac{x}{2} + \frac{y}{3} = \frac{3x + 2y}{6}$$

б) $$\frac{c}{4} - \frac{d}{12} = \frac{3c - d}{12}$$

в) $$\frac{a}{b} - \frac{b^2}{a} = \frac{a^2 - b^3}{ab}$$

г) $$\frac{3}{2x} - \frac{2}{3x} = \frac{9 - 4}{6x} = \frac{5}{6x}$$

д) $$\frac{5x}{8y} + \frac{x}{4y} = \frac{5x + 2x}{8y} = \frac{7x}{8y}$$

e) $$\frac{17y}{24c} - \frac{25y}{36c} = \frac{51y - 50y}{72c} = \frac{y}{72c}$$

ж) $$\frac{1}{5a} - \frac{8}{25a} = \frac{5 - 8}{25a} = -\frac{3}{25a}$$

з) $$\frac{3b}{4c} + \frac{c}{2b} = \frac{3b^2 + 2c^2}{4bc}$$