Passage

Directions: Read the following information and answer the given question. A, B, C and D are working in a team to complete a project in 5 days. A and B together can complete the work in 10 days, C alone can complete the work in 15 days and A and D together can complete the work in 20 days.

If C and D can complete their work alone in 5 days before their estimated time due to their increased efficiency, then how many days are all these four persons going to take to complete the whole project work together?