\[c = 5\frac{1}{6}:\]
\[- 5,7 - c = - 5,7 - 5\frac{1}{6} =\]
\[= - \left( 5\frac{7}{10} + 5\frac{1}{6} \right) =\]
\[= - \left( 5\frac{21}{30} + 5\frac{5}{30} \right) =\]
\[= - 10\frac{26}{30} = - 10\frac{13}{15}.\]