After Ken’s funeral, his wife Helen decided to offer his collection of CDs to members of his local Jazz Club. As there were so many CDs, it was not possible to take all of them to the first meeting of the club; so 60% of the collection was put into a box, from which members could take the ones they wanted. By the end of the meeting half of these had been taken. A week later, a further 30% of the original collection was added to the box. During this meeting, three quarters of the CDs in the box were taken. At the third meeting, the rest of the collection was added to the box. There were now 40 CDs for the members to choose from. How many CDs were there in the original collection?