The 55% is an outdated figure that is no longer relevant. In the days when films had legs, that's usually the average percentage of the gross that studios ended up getting. But studios get a much, much larger cut of the gross on opening weekend which diminishes as time goes on, so these days with films having huge openings and no legs to speak of the 55% is not close to accurate. And if you want to factor in marketing costs, you must also factor in product placement deals and merchandising.
KangConquers, if your figures and math were even close to correct studios would *never* make movies that cost $150 million. I hope you realize that.