[tex][2,1:\dfrac{(4,5\cdot1\frac23+3,75)\cdot\frac7{135}}{1-\frac{10}{27}:\frac56}]:2,5=[2\frac1{10}:\dfrac{(4\frac12\cdot1\frac23+3\frac34)\cdot\frac7{135}}{1-\frac{10}{27}:\frac56}]:2\frac12=[/tex]
[tex][\frac{21}{10}:\dfrac{(\frac92\cdot\frac53+\frac{15}4)\cdot\frac7{135}}{1-\frac{10}{27}\cdot\frac65}]:\frac52=[\frac{21}{10}:\dfrac{(\frac{15}2+\frac{15}4)\cdot\frac7{135}}{1-\frac{4}{9}}]\cdot\frac25=[/tex]
[tex][\frac{21}{10}:\dfrac{(\frac{30}4+\frac{15}4)\cdot\frac7{135}}{\frac{5}{9}}]\cdot\frac25=[\frac{21}{10}:\dfrac{\frac{45}4\cdot\frac7{135}}{\frac{5}{9}}]\cdot\frac25=[\frac{21}{10}:\dfrac{\frac{7}{12}}{\frac{5}{9}}]\cdot\frac25=[\frac{21}{10}:(\frac{7}{12}:\frac{5}{9})]\cdot\frac25=[/tex]
[tex][\frac{21}{10}:(\frac{7}{12}\cdot\frac{9}{5})]\cdot\frac25=[\frac{21}{10}:\frac{21}{20}]\cdot\frac25=[\frac{21}{10}\cdot\frac{20}{21}]\cdot\frac25=2\cdot\frac25=\frac45[/tex]
