(6 3/5-3 3/14)×5 5/6/(21-1,25)÷2,5

[latex](6 \frac{3}{5}-3 \frac{3}{14})*5 \frac{5}{6} : (21-1,25):2,5=(\frac{33}{5}-\frac{45}{14})*\frac{35}{6} : (21- \frac{5}{4} ): \frac{5}{2} = \\ \\ =(\frac{33*14-45*5}{70})*\frac{35}{6} : (\frac{21*4-5}{4} ): \frac{5}{2}=\frac{237}{70}*\frac{35}{6} : \frac{79}{4}: \frac{5}{2} = \\ \\ =\frac{79}{4} : \frac{79}{4}: \frac{5}{2}=1:\frac{5}{2}=1*\frac{2}{5}=\frac{2}{5}[/latex]