Assuming the complete question is;
Consider the balanced equation below;
4NH3 + 3O2 = 2N2 +6H2O
What is the mole ratio of NH3 to N2;
From the balanced equation; the mole ratio of NH3 to N2 is 4:2.
The mole ratio is the ratio of moles of one substance to the number of moles of another substance in a balanced equation. In the above equation; 4 moles of ammonia requires 3 moles of oxygen to produce two moles of nitrogen and six moles of water.