\(a.=\left(\dfrac{-3}{5}+\dfrac{-4}{5}+\dfrac{7}{5}\right)+\dfrac{7}{21}=\dfrac{7}{21}.\)
\(b.\dfrac{-3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)=\left(\dfrac{-3}{17}+\dfrac{3}{17}\right)+\dfrac{2}{3}=\dfrac{2}{3}.\)
\(c.=\left(\dfrac{-5}{21}+\dfrac{-16}{21}\right)+1=-1+1=0.\)
\(d.=\left(\dfrac{5}{7}+\dfrac{-12}{7}\right)+\left(\dfrac{9}{23}+\dfrac{14}{23}\right)=-1+1=0\)
\(e.=\left(\dfrac{3}{17}+\dfrac{14}{17}\right)+\left(\dfrac{-5}{13}+\dfrac{-8}{13}\right)+\left(\dfrac{-18}{35}+\dfrac{17}{-35}\right)\)
\(=1+\left(-1\right)+\left(-1\right)=-1.\)
\(f.=\dfrac{-1}{16}+\dfrac{-5}{16}+\dfrac{-10}{16}=-1.\)
\(g.=\left(\dfrac{-4}{11}\cdot\dfrac{11}{-4}\right)\cdot\dfrac{5}{15}=1\cdot\dfrac{5}{15}=\dfrac{1}{3}.\)
\(h.=\dfrac{7}{36}+\dfrac{8}{9}-\dfrac{2}{3}=\dfrac{7}{36}+\dfrac{32}{36}-\dfrac{24}{36}=\dfrac{15}{36}=\dfrac{5}{12}.\)
\(i.=\dfrac{4}{7}-\dfrac{5}{8}-\dfrac{3}{28}=\dfrac{32}{56}-\dfrac{35}{56}-\dfrac{6}{56}=-\dfrac{9}{56}.\)
\(l.=-\dfrac{6}{11}:\dfrac{12}{55}=-\dfrac{5}{2}.\)
\(A=\dfrac{7}{12}+\dfrac{5}{12}:6-\dfrac{11}{36}\)\(=\left(\dfrac{7}{12}+\dfrac{5}{12}\right):6-\dfrac{11}{36}=1:6-\dfrac{11}{36}=\dfrac{1}{6}-\dfrac{11}{36}=-\dfrac{5}{36}.\)
\(B=\left(\dfrac{4}{5}+\dfrac{1}{2}\right):\left(\dfrac{3}{13}-\dfrac{8}{13}\right)=\dfrac{13}{10}:\left(-\dfrac{5}{13}\right)=-\dfrac{169}{50}.\)
\(C=\left(\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}\right):\left(\dfrac{5}{12}+1-\dfrac{7}{11}\right)\)\(=\dfrac{115}{132}:\dfrac{103}{132}=\dfrac{115}{103}.\)'
\(D=1\dfrac{3}{8}+\dfrac{1}{8}:\left(0,75-\dfrac{1}{2}\right)-25\%\cdot\dfrac{1}{2}\)
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