AHSME 1975 Problem 17

A man can commute either by train or by bus. If he goes to work on the train in the morning, he comes home on the bus in the afternoon; and if he comes home in the afternoon on the train, he took the bus in the morning. During a total of $x$ working days, the man took the bus to work in the morning $8$ times, came home by bus in the afternoon $15$ times, and commuted by train (either morning or afternoon) $9$ times. Find $x$. $\textbf{(A)}\ 19 \textbf{(B)}\ 18 \textbf{(C)}\ 17 \textbf{(D)}\ 16 \\ \textbf{(E)}\ \text{ not enough information given to solve the problem}$