( 23 5/9 - 22 7/12) . ( 24/42 + 21/165 + 39/143) / 3,1^2 -8,76

$\frac{(23\frac{5}{9} - 22\frac{7}{12}) .(\frac{24}{42}+ \frac{21}{165} +\frac{39}{143} )}{3,1²-8,76}$

= $\frac{(\frac{212}{9} - \frac{271}{12}). (\frac{269}{385} + \frac{39}{143} ) }{9,61-8,76}$ 

= $\frac{\frac{35}{36}.\frac{34}{35} }{0,85}$ 

= $\frac{\frac{17}{18} }{0,85}$ 

= $\frac{10}{9}$