Using the balanced equation you find the number moles in 890.1 grams of nitrogen.
Then you use the ration of nitrogen to ammonia.
This is a 1:2 ratio
890.1g/28gmol-1=31.79moles of nitrogen
This is then used to find the moles of ammonia
31.79*2(using the mole ration)=63.58moles of ammonia
to find the mass of ammonia you multiply the moles by the RMM of ammonia=63.58*17 gmol-1=1080.86 g