4NH3+7O2->4NO2+6H2O If [No2] is changing at a rate of 2.0mole/L second what rate is [NH3] changing at?

4NH₃ + 7O₂ → 4NO₂ + 6H₂O
Mole ratio NH₃ : NO₂ = 4 : 4 = 1 : 1

NO₂ is formed and thus its rate of change is positive, while NH₃ is consumed and its rate of change is negative.
The rate of change of [NO₂] = +2.0 mol/L
Hence, the rate of change of [NH₃] = -2.0 mol/L

2.0mole/L ... same rater