Найдите сумму или разность: 1) a) $$\frac{1}{3} + \frac{5}{6}$$; 2) a) $$\frac{3}{11} - \frac{1}{13}$$; 3) a) $$\frac{5}{34} - \frac{41}{51}$$

1) a) $$\frac{1}{3} + \frac{5}{6} = \frac{2}{6} + \frac{5}{6} = \frac{7}{6} = 1\frac{1}{6}$$ 2) a) $$\frac{3}{11} - \frac{1}{13} = \frac{3 \cdot 13}{11 \cdot 13} - \frac{1 \cdot 11}{13 \cdot 11} = \frac{39}{143} - \frac{11}{143} = \frac{28}{143}$$ 3) a) $$\frac{5}{34} - \frac{41}{51} = \frac{5 \cdot 3}{34 \cdot 3} - \frac{41 \cdot 2}{51 \cdot 2} = \frac{15}{102} - \frac{82}{102} = -\frac{67}{102}$$