From equation,
3 mol FeO reacts with 2 mol Al
Finding mass of FeO
no of mol=mass/Mr
3=mass/(55.8+16)
mass = 215.4g
Finding mass of Al
no of mol= mass/Ar
2= mass/27
mass=54g
215.4g of FeO reacts with 54g Al
79.8g of FeO reacts with 54/215.4 × 79.8 = 20g Al