<PRE><B>Question 900266</B>
1/a+1/b=1/x
1/20+1/b=1/15
3/20+1/b=4/60
1/b=1/60
b=60
check
1/20+1/60=1/15
3/60+1/60=4/60
4/60=4/60 
ok

6/20+6/60+x/60=1
18/60+6/60+x/60=1
24/60+x/60=1
x/60=36/60=6/10
A and B did 24/60=.4 together
x=36 days for B to finish .6 of the job alone


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