AHSME 1951 Problem 13

$A$ can do a piece of work in $9$ days. $B$ is $50\%$ more efficient than $A$. The number of days it takes $B$ to do the same piece of work is: $\textbf{(A)}\ 13\frac {1}{2} \textbf{(B)}\ 4\frac {1}{2} \textbf{(C)}\ 6 \textbf{(D)}\ 3 \textbf{(E)}\ \text{none of these answers}$