$$\left. \begin{array} { l } { \quad A = x + 5 + ( 3 x + 1 ) ( x + 5 ) } \\ { B = ( 3 x - 1 ) - ( 3 x - 1 ) ^ { 2 } } \\ { C = x + 4 + ( x + 6 ) ( 2 x + 1 ) + 2 } \end{array} \right.$$
