Kalon and his friend marna own a chimney sweep service company. working together, they can clean a chimney in 1 5/7 hours. if it takes kalon 4 hours to clean a 20-foot chimney by himself, how long does it take marna to clean the same size chimney by herself?

It takes 3 hours for Marna to clean the same size chimney by herself.

Step-by-step explanation:

Kalon and his friend Marna can clean a chimney in hours

They can do a part of work in 1 hour =

Kalon can complete work in 4 hours

He can do a part of work in 1 hour =

So,  Marna  can do a part of work in 1 hour =  

                                                                       =  

So, Marna can part of work in hour = 1

Marna can complete work in hour = 3

Hence it takes 3 hours for Marna to clean the same size chimney by herself.

11 feet 6 inches and 8 feet 6 inches