Selected financial information is provided below for three major pharmaceuticals: GlaxoSmithKline (Britain), Sanofi-Aventis (France), and Pfizer U.S.). GlaxoSmithKline's numbers were taken from the 2008 SEC Form 20-F, it uses IFRS, and the numbers are expressed in British pounds; the numbers for Sanofi-Aventis were also taken from the 2008 SEC Form 20-F and it too uses IFRS, but the numbers are expressed in Euros: Pfizer is a U.S. company that uses U.S. GAAP, and the numbers are expressed in dollars and were taken from the 2008 SEC Form 10-K. As of the end of 2008, 1 U.S. dollar was equivalent to .69 British pounds and .71 Euros. All numbers are in billions

a. Which company is the largest, and by how much?b. Explain why it may be difficult to clearly state which is the largest.

GlaxoSmithKline Sanofi-Aventis Pfizer Sales Total assets Shareholders' equity 27.5 48.2 39.3 7.9 71.9 III.I 45.1 57.5