Answer:
Step-by-step explanation:
Given that Kalon and his friend Marna own a chimney sweep service company. Working together, they can clean a chimney in 1 5/7 hours and it takes Kalon 4 hours to clean a 20-foot chimney by himself.
i.e. Kalon can do in one hour 1/4 of the work
Marna can do in one hour 1/x of the work
(assuming total x hours Marns taes to clean the same size chimney)
Together they clean
\(\frac{7}{12}\)
\(\frac{1}{4} +\frac{1}{x} =\frac{7}{12}\)
Simplify to get
\(12(x+4)=28x\\3x+12=7x\\4x=12\\x=3\)
Marna takes 3 hours to clean the same size chimney
