The combustion of ammonia produces no and water. how much ammonia will be required to produce 10.0 mol of water

The combustion of ammonia can be described using the following reaction:
4NH3(g) + 5O2(g)  ---> 4NO(g) + 6H2O(g)
From the balanced equation above, we can note that 4 moles of ammonia lead to the formation of 6 moles of water.
Therefore, to know the number of moles of ammonia that will form 10 moles of water, we will simply do cross multiplication as follows:
number of moles of ammonia = (10*4) / 6 = 6.6667 moles

Now, we need to get the mass of the ammonia needed. This means that we need to get the mass of 6.6667 moles of ammonia. To do so, we will use the following rule:
number of moles = mass / molar mass
number of moles = 6.6667 moles
mass is the quantntity we want to get
molar mass of ammonia = 14 + 3(1) = 17 grams
Therefore:
6.6667 = mass / 17
mass = 113.3334 grams

Perimeter? wheres the answers