Question 571229
    if it takes 4 hours for a group of people to paint a house and 6 hours for another group of people to paint another house, How long will it take for both groups of people to paint a house together?
Let x = time (hours) it takes for both groups
then
x(1/4 + 1/6) = 1
multiply both sides by 12:
x(3 + 2) = 12
x(5) = 12
x = 12/5
x = 2.4 hours