Time taken to paint a wall is inversely proportional to the number of painters working on it. If it takes 4 painters 6 days to complete the job, how many days longer will it take if there are only 3 painters working ?

Question

$\begin{array}{1 1} (a)\; 7 \\ (b)\; 2 \\ (c)\; 6 \\ (d)\;12 \end{array}$