Alex can remodel a bathroom in 2 days. Abraham can remodel the same bathroom in 4 days. How long will it take them to remodel the bathroom if they work together?
Alex's rate = b/2
Abr's rae = b/4
combined rate = b/2 + b/4 = 3b /4
time to do together = b/(3b/4)
= b(4/(3b)) = 4/3 days