Answer:
Well, if only 3% of the ticket holders are already seated, then we can assume that 97% of them haven't arrived yet. So, we can set up a proportion: 
3/100 = 144/x 
Solving for x, we get: 
x = (144*100)/3 = 4800 
So, there were 4800 tickets sold for the musical. Let's hope they show up soon!