Ammonia reacts with O₂ to form either NO(g) or NO₂(g) according to the following UNBALANCED equations: NH₃(g) + O₂(g) → NO(g) + H₂O(g)

NH₃(g) + O₂(g) → NO₂(g) + H₂O(g)
In one experiment 6.00 moles of NH₃(g) and 15.00 moles of O₂(g) were placed in a closed flask and allowed to react. After the reaction was complete, 5.15 moles of O₂(g) remained and all of the NH₃(g) had reacted. Calculate the number of moles of NO(g) formed in the reaction mixture.