If you use all portions of both trips, why shouldn't it be legal?

Fly to LAS for Comdex. Wanted to spend Sunday in LAX, and flew back. So overall on my comdex trip, I've been in LAX 4 times. Twice on my way to/from LAS, and for that Sunday. Was on different tickets, since that trip back to LAX was personal and had nothing to do with my business.