a) $$ \frac{8}{13} + \frac{3}{13} = \frac{8+3}{13} = \frac{11}{13}$$
б) $$\frac{31}{60} + \frac{29}{60} = \frac{31+29}{60} = \frac{60}{60} = 1$$
Ответ: a) 11/13; б) 1