$\text{a)}\frac{\left(12\frac{3}{4}-8\frac{3}{8}\right)\cdot 0,3}{0,2}=\frac{\left(12\frac{6}{8}-8\frac{3}{8}\right)\cdot \frac{3}{10}}{\frac{1}{5}}=\frac{4\frac{3}{8}\cdot \frac{3}{10}}{\frac{1}{5}}=\frac{\frac{{\cancel{35}}^7}{8}\cdot \frac{3}{{\cancel{10}}_2}}{\frac{1}{5}}=\frac{\frac{21}{16}}{\frac{1}{5}}=\frac{21}{16}\cdot \frac{5}{1}=\frac{105}{16}=6\frac{9}{16}$  

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$\text{b)}\frac{\left(9\frac{5}{24}-6\frac{7}{20}\right):2\frac{1}{3}+0,6}{0,2}=\frac{\left(9\frac{25}{120}-6\frac{42}{120}\right):\frac{7}{3}+\frac{3}{5}}{\frac{1}{5}}=\frac{\left(8\frac{145}{120}-6\frac{42}{120}\right):\frac{7}{3}+\frac{3}{5}}{\frac{1}{5}}=\frac{2\frac{103}{120}:\frac{7}{3}+\frac{3}{5}}{\frac{1}{5}}=\frac{\frac{{\cancel{343}}^{49}}{120}\cdot \frac{3}{{\cancel{7}}_1}+\frac{3}{5}}{\frac{1}{5}}=\frac{\frac{147}{120}+\frac{3}{5}}{\frac{1}{5}}=\frac{\frac{147}{120}+\frac{72}{120}}{\frac{1}{5}}=\frac{\frac{219}{120}}{\frac{1}{5}}=\frac{219}{{\cancel{120}}_{24}}\cdot \frac{{\cancel{5}}^1}{1}=\frac{219}{24}=\frac{73}{8}=9\frac{1}{8}$  

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$\text{c)}\frac{2\frac{5}{8}-\frac{2}{3}\cdot 2\frac{5}{14}}{\left(3\frac{1}{12}+4,375\right):19\frac{8}{9}}=\frac{2\frac{5}{8}-\frac{{\cancel{2}}^1}{{\cancel{3}}_1}\cdot \frac{{\cancel{33}}^{11}}{{\cancel{14}}_7}}{\left(3\frac{1}{12}+4\frac{3}{8}\right):19\frac{8}{9}}=\frac{2\frac{5}{8}-\frac{11}{7}}{\left(3\frac{2}{24}+4\frac{9}{24}\right):19\frac{8}{9}}=\frac{2\frac{5}{8}-1\frac{4}{7}}{7\frac{11}{24}:\frac{179}{9}}=\frac{2\frac{35}{56}-1\frac{32}{56}}{\frac{{\cancel{179}}^1}{24}\cdot \frac{9}{{\cancel{179}}_1}}=\frac{1\frac{3}{56}}{\frac{9}{24}}=\frac{59}{56}\cdot \frac{24}{9}=\frac{59}{{\cancel{56}}_7}\cdot \frac{{\cancel{8}}^1}{3}=\frac{59}{21}=2\frac{17}{21}$  

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$\text{d)}\frac{1+\frac{1}{2}\cdot \frac{1}{0,25}}{6-\frac{46}{1+2,2\cdot 10}}=\frac{1+\frac{1}{2}\cdot \frac{1}{\frac{1}{4}}}{6-\frac{46}{1+22}}=\frac{1+\frac{1}{2}\cdot 4}{6-\frac{46}{23}}=\frac{1+2}{6-2}=\frac{3}{4}$  

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$\text{e)}\left(1,5291-\frac{14,53662}{3-0,095}\cdot 0,305\right):0,12=\left(1,5291-\frac{14,53662}{2,905}\cdot 0,305\right):0,12=\left(1,5291-5,004\cdot 0,305\right):0,12=\left(1,5291-1,52622\right):0,12=0,00288:0,12=0,024$  

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$\text{f)}\frac{5\frac{10}{63}-4\frac{25}{84}}{\left(2\frac{1}{3}-1\frac{1}{9}\right):4-\frac{3}{4}}:31=\frac{5\frac{40}{252}-4\frac{75}{252}}{\left(2\frac{3}{9}-1\frac{1}{9}\right):4-\frac{3}{4}}:31=\frac{4\frac{292}{252}-4\frac{75}{252}}{1\frac{2}{9}:4-\frac{3}{4}}:31=\frac{\frac{217}{252}}{\frac{11}{9}\cdot \frac{1}{4}-\frac{3}{4}}:31=\frac{\frac{217}{252}}{\frac{11}{36}-\frac{3}{4}}:31=\frac{\frac{217}{252}}{\frac{11}{36}-\frac{27}{36}}:31=\frac{\frac{217}{252}}{-\frac{16}{36}}:31=\frac{\frac{217}{252}}{-\frac{4}{9}}:31=\frac{217}{{\cancel{252}}_{28}}\cdot \left(-\frac{{\cancel{9}}^1}{4}\right):31=-\frac{217}{259}:31=-\frac{{\cancel{217}}^7}{112}\cdot \frac{1}{{\cancel{31}}_1}=-\frac{7}{112}=-\frac{1}{16}$