Read the passage below and solve the questions based on it.
A group of 10 people, each with a different capacity to work, is assigned to complete a certain work. They work in such a way that only two people work on any given day, with no group of the same two people working on more than one day. By working in this manner, they could finish only 3/4th of the work by the time all the possible pairs of people had worked once. The remaining part of the work was then finished by all of them working together.
What is the number of days for which all of them worked together?