I'll reply again later. I'm still working on this and don't want to cheat by looking up the answer. Until then I assume you are right but that's not the answer I have, so far, Ms. Pus-filled Boil (gags).
Right. You know the over all length (of time) = 180 minutes. You also know the length of three short lengths in terms of X: X, 2X and 48. Adding all these together and solving for X, gives the answer. That took a whole day for me to figure out. I'm trying to keep my mind from slowing down too much. It shouldn't take that long.