Question 196608
Q. Bill and James can do together a piece of work in 30 days.
 James alone can finish the work in 60 days, both began the work together
 but Bill left 3 days before the completion of the work. 
how long will it take to finish the work.?
:
Since working together it takes 30 days, and working alone J can do half of it
30/60 in 30 day; then B's time alone is 60 days also
:
Let t = time required to finish the job
Let the completed job = 1
:
A simple equation
Bill's time + J's time = the completed job
{{{(t-3)/60}}} + {{{t/60}}} = 1
Multiply eq by 60
(t-3) + t = 60
:
2t - 3 = 60
:
2t = 63
:
t = {{{63/2}}}
t = 31.5 days to do the job