Question

Suppose one painter can paint the entire house in twelve hours, and the second painter takes eight hours to paint a similarly-sized house. how long would it take the two painters together to paint the house?

Answer 1

There is a formula for this:
Time = (Worker1 Time * Worker2 Time) / (Worker1 Time + Worker2 Time)

Time = (12 * 8) / (12 + 8)
Time = 96 / 20
Time = 4.8 Hours

Source:http://www.1728.org/work.htm