Question: how many moles of oxygen are required to react completely with aluminum?
Answer: For this equation, the mole ratio is 3 moles of O2 : 4 moles of Al. So, you would then multiply: 14.8 moles*(3/4) = 11.1 moles. 11.1 moles O2 are needed to react completely with 14.8 moles of Al.