Final answer:
It would take Maria approximately 28/41 hours to clean the chimney by herself.
Step-by-step explanation:
To answer this question, we can use the concept of work rates. Let's assume that Maria takes x hours to clean the chimney by herself. In 1 hour, Kalyn can clean 1/4 of the chimney, since it takes him 4 hours to clean the whole chimney. Similarly, in 1 hour, Maria can clean 1/x of the chimney. Working together, in 1 hour, they can clean 1/4 + 1/x of the chimney. We know that together, they can clean the chimney in 1 5/7 hours, or 12/7 hours. Setting up an equation:
1/4 + 1/x = 12/7
We can solve for x by multiplying through by 28x to eliminate the fractions:
7x + 28 = 48x
41x = 28
x = 28/41
Therefore, it would take Maria approximately 28/41 hours to clean the chimney by herself.