Answer:
165920160 ways
Step-by-step explanation:
Number of songs in library (n) = 115
Number of songs in Playlist (r) = 4
Since the order is important:
nPr = n! / (n-r)!
115P4 = 115! / (115 - 4)! = 115! / 111! = (115 * 114 * 113 * 112)
= 165920160 ways