Due to its severity, bird flu, or avian flu, has caused great concern worldwide. The main drug for its treatment is Tamiflu. Tamiflu is an antiviral drug and acts to minimize the effects of bird flu by inhibiting the protein neuraminidase that lives on the surface of the flu virus. Analysis of Tamiflu shows it is composed of 61.5% carbon (C), 8.97% hydrogen (H), 8.93% nitrogen (N) and 20.6% oxygen (O) by mass. Below is a ball-and-stick picture of Tamiflu. What is the actual formula of Tamiflu?