Answer:
It would take 10 days to the first constructor and 15 days to the second one to finish the room.
Explanation:
Time to finish the room with both constructors: 6 days.
Time to finish the room by the first constructor only: x days.
Time to finish the room by the second constructor only: (x + 5) days.
If we associate all that, 1 day work of both constructors working at the same time would be

1 day work of the first is:

1 day work of the second is:

Now, we need to find the variable, using the following equation

Then, we need to find two numbers which product is 30, and which difference is 7. Those numbers are 10 and 3, because 10 times 3 is 30, and 10 minus 3 is 7.

Using the zero factor property, we have

But, only the positive number makes sense. Replacing the value in each expression we have
First constructor:
days.
Second constructor:
days,
Threfore, it would take 10 days to the first constructor and 15 days to the second one to finish the room.