\[7\frac{11}{12} + 6\frac{1}{15} - 8,3 =\]
\[= 7\frac{11^{\backslash 5}}{12} + 6\frac{1^{\backslash 4}}{15} - 8\frac{3^{\backslash 6}}{10} =\]
\[= 5\frac{55 + 4 - 18}{60} = 5\frac{41}{60}\]