№5. Выполните действ a) 10\frac{4}{15}+9\frac{11}{15}-8\frac{1}{30}; б) 19\frac{1}{17}-8\frac{9}{17}-3\frac{15}{17}; в) (6\frac{7}{12}+8\frac{5}{12})-7\frac{16}{21}-4.

№5. Выполните действия:

a) $$10\frac{4}{15}+9\frac{11}{15}-8\frac{1}{30}=(10+9-8)+(\frac{4}{15}+\frac{11}{15}-\frac{1}{30})=11+\frac{4}{15}+\frac{11}{15}-\frac{1}{30}=11+\frac{8}{30}+\frac{22}{30}-\frac{1}{30}=11+\frac{8+22-1}{30}=11+\frac{29}{30}=11\frac{29}{30}$$

Ответ: $$11\frac{29}{30}$$

б) $$19\frac{1}{17}-8\frac{9}{17}-3\frac{15}{17}=(19-8-3)+(\frac{1}{17}-\frac{9}{17}-\frac{15}{17})=8+\frac{1-9-15}{17}=8+\frac{-23}{17}=8-\frac{23}{17}=8-1\frac{6}{17}=7-\frac{6}{17}=6+\frac{17}{17}-\frac{6}{17}=6+\frac{11}{17}=6\frac{11}{17}$$

Ответ: $$6\frac{11}{17}$$

в) $$(6\frac{7}{12}+8\frac{5}{12})-7\frac{16}{21}-4=(6+8)+(\frac{7}{12}+\frac{5}{12})-7\frac{16}{21}-4=14+\frac{7+5}{12}-7\frac{16}{21}-4=14+\frac{12}{12}-7\frac{16}{21}-4=14+1-7\frac{16}{21}-4=15-(7+4)-\frac{16}{21}=15-11-\frac{16}{21}=4-\frac{16}{21}=3+\frac{21}{21}-\frac{16}{21}=3+\frac{5}{21}=3\frac{5}{21}$$

Ответ: $$3\frac{5}{21}$$