Question 376735
Let D = number of hours for painting job, r = number of rooms to paint/painted, and m = number of men doing the painting.
Then D is directly proportional to r but inversely proportional with m.  Hence 
{{{D = (kr)/m}}}, where k is a constant of proportionality.  To find k, 
{{{9 = (k*4)/3}}}, or k = 27/4.  Hence {{{D = (27r)/(4m)}}}.  If m = 1 and r = 1, then D = 27/4 = 6.75, or 6 hours and 45 minutes.