Chemistry

Caffeine is made up of 49.5% C, 5.2% H, 16.5% O, and 28.9% N. A solution of 8.25g of caffeine and 100 ml of benzene (density 0.887g/ml) freezes at 3.03°©. Pure benzene (kf= 5.10°©) freezes at 5.50°©. What are the simplest and molecular formula for caffeine?