Question 418517
the job is half done (10/20) when the 1st man quits


the 2nd man does the second half in 12 days , so it would take him 24 days to do the job alone


in the 10 days they worked together , the 2nd man did 10/24 ,(5/12), of the job
___ since together they did 1/2 ,(6/12), ; this means that the 1st man did 1/12 ,(6/12 - 5/12), in 10 days
___ it would take the 1st man 120 days ,(10 / 1/12), to do the job alone