Given reaction and its balanced equation is
From the equation
Looking at the mole ratio between FeO : Al, by looking at the equation, you can see that the mole ratio is 3 : 2.
So, Imagine if 3 moles of FeO gives you 2 moles of Al,
then 1.2 moles of Feo should give you:
Therefore, 0.80 moles of Al are needed to react completely with 1.2 moles of FeO.