Question 287626
What can be done in 1 hour?
Lisa can type 1/5 of the paper in hour.
Bill Can type 1/B of the paper in 1 hour.

TOGETHER they can type 1/2 the paper in one hour. Soooo

1/5+1/B=1/2 (do the math!)
B=10/3  BUT let's check this!

1/5+ 1/10/3=3/10    1/5+3/10=2/10+3/10=5/10=1/2

The answer is three hours and 20 minutes