б)71$$\frac{8}{13}$$+8$$\frac{12}{13}$$+$$\frac{9}{13}$$;

б) 71$$\frac{8}{13}$$+8$$\frac{12}{13}$$+$$\frac{9}{13}$$ = (71 + 8) + ($$\frac{8}{13}$$ + $$\frac{12}{13}$$ + $$\frac{9}{13}$$) = 79 + $$\frac{8 + 12 + 9}{13}$$ = 79 + $$\frac{29}{13}$$ = 79 + 2$$\frac{3}{13}$$ = 81$$\frac{3}{13}$$

Ответ: 81$$\frac{3}{13}$$