Sulfur and fluorine form several different compounds including sulfur hexafluoride and sulfur tetrafluoride. Decomposition of a sample of sulfur hexafluoride produced 4.46 g of fluorine and 1.27 g of sulfur, while decomposition of a sample of sulfur tetrafluoride produced 4.42 g of fluorine and 1.89 g of sulfur.
Mass of fluorine per gram of sulfur is just:
Mass fluorine / mass sulfur
For SF6: 4.46 g / 1.27 g = 3.51
For SF4: 4.42 g / 1.89 g = 2.33