In how many ways can 3 girls and 9 boys can be seated in two vans having 3 numbered seats in the front and 4 numbered seats at the back so that the 3 girls are to be seated together in the back row?

Question

$\begin{array}{1 1} 6.^{11}P_9 \\ 12.^{11}P_9 \\ 24.^{11}P_9 \\ 30.^{11}P_9 \end{array}$