Trey's rate = 1/40
Marcus rate = 1/20
combined rate = 1/40 + 1/20 = 3/40
time at combined rate = 1/(3/40)
= 40/3 minutes
trey can clean a room in 40 minutes. his brother Marcus can clean the same room in 20 minutes. how long will it take them to clean the room if they work together?
1 answer
1 answer