$$\left. \begin{array} { l } { [ 18 + ( - 78 ) ] \div [ ( + 12 ) - ( + 8 ) ] } \\ { [ 18 - ( - 6 ) ] \times 2 + ( - 5 ) } \\ { \frac { ( - 10 ) + 7 ( - 2 ) } { ( - 6 ) } } \end{array} \right.$$
