Since they expect to put 16 songs, but actually end up putting 50% more, we can do 16 * 150 % which would equal 24 songs that they actually put on their CD.
During the editing process, they removed 75 % of the songs they put on their CD. Since they put 24 songs on their CD, we can do:
24 * 25 % (because this would equal the songs left after the editing process, and not the actual number of songs removed, which is 75 %) which would equal 6 songs.
There would be 6 songs left on their Final CD.