If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house?
the answer is 2 hrs and 24 min. How did they come up with that?
In twelve hours, sally can paint 3, and john 2, or five houses together.
combined rate=5houses/12hours
1house=rate*time=5/12 * time
time= 12/5 hrs