6\frac{11}{12}+8\frac{13}{18}; 2\frac{3}{16}+1\frac{7}{24}+3\frac{1}{12}; 1\frac{8}{21}+4\frac{3}{14}+2\frac{2}{7}; 12\frac{11}{12}-5\frac{13}{18}; 13-7\frac{3}{16}; 10-5\frac{12}{35}; 15-12\frac{16}{17}; 8-4\frac{5}{22}.

Выполним вычисления по порядку: 1) $$6\frac{11}{12}+8\frac{13}{18} = 6\frac{33}{36}+8\frac{26}{36} = 14\frac{59}{36} = 15\frac{23}{36}$$ 2) $$2\frac{3}{16}+1\frac{7}{24}+3\frac{1}{12} = 2\frac{9}{48}+1\frac{14}{48}+3\frac{4}{48} = 6\frac{27}{48} = 6\frac{9}{16}$$ 3) $$1\frac{8}{21}+4\frac{3}{14}+2\frac{2}{7} = 1\frac{16}{42}+4\frac{9}{42}+2\frac{12}{42} = 7\frac{37}{42}$$ 4) $$12\frac{11}{12}-5\frac{13}{18} = 12\frac{33}{36}-5\frac{26}{36} = 7\frac{7}{36}$$ 5) $$13-7\frac{3}{16} = 12\frac{16}{16}-7\frac{3}{16} = 5\frac{13}{16}$$ 6) $$10-5\frac{12}{35} = 9\frac{35}{35}-5\frac{12}{35} = 4\frac{23}{35}$$ 7) $$15-12\frac{16}{17} = 14\frac{17}{17}-12\frac{16}{17} = 2\frac{1}{17}$$ 8) $$8-4\frac{5}{22} = 7\frac{22}{22}-4\frac{5}{22} = 3\frac{17}{22}$$