Question 174353
so prof painter can do 1/7 of the job per hour 
and John can do 1/12 of the job per hour
together they can do 
:
1/12+1/7=7/84++12/84=19/84 of the job per hour
:
19/84(t)=1
:
{{{highlight(t=84/19)}}} hours.....which is appx 4.42 hours