Answer:
If the homeowner helps the roofer it will take 4 days to roof the house.
Explanation:
Given that a homeowner estimates that it will take 11 days to roof his house, while a professional roofer estimates that he could roof the house in 6 days, to determine how long it will take if the homeowner helps the roofer the following calculation must be done:
1/6 + 1/11 = X
0.1666666 + 0.09090909 = X
0.25 = X
1/4 = X
Therefore, if the homeowner helps the roofer it will take 4 days to roof the house.