<PRE><B>Question 1180674</B>


Alan takes 6 days less than Bob to finish task at work. 

let Bob take x days to finish the job alone
Bob does 1/x of thejob in 1 day
alan does 1/(x-6) of the job in 1 day
Alan will take x-6 days to finish the job alone

both Alan and Bob work together, they can finish the work in 4 days

Together they do  1/4 of the job in 1 day
1/x + 1/(x-6) = 1/4

Multiply the terms by x(x-6)*4

4(x-6) +4x = x(x-6)

4x-24 +4x= x^2-6x

x^2-14x+24=0
(x-12)(x-2)=0

x=12 OR 2 
2 is not possible

Bob takes 12 days alone








</PRE>