We have the following information of a construction project, which forms a function in terms of the construction of a building in a number of days.

After 2 days, they have completed 10% of the building.

After 4 days, they have completed 20% of the building.

After 5 days, they have completed 30% of the building.

How long would it take for the construction to be finished?

10 Days?
15 Days?
20 Days?
25 Days?