AMC 8 2008 Problem 10

The average age of the $6$ people in Room A is $40$. The average age of the $4$ people in Room B is $25$. If the two groups are combined, what is the average age of all the people? $\textbf{(A)}\ 32.5 \textbf{(B)}\ 33 \textbf{(C)}\ 33.5 \textbf{(D)}\ 34 \textbf{(E)}\ 35$