What criteria based on expressing standard rate of reaction?

When given the reaction: $\ce{NO2}$ reacts with $\ce{O2}$ to produce $\ce{N2O5}$, how do I calculate the rate of consumption of $\ce{NO2}$ when the rate of the reaction= 0.02 M/s? 


I am confused about which of these expressions of reaction rate can be used to calculate the rate of consumption of $\ce{NO2}$. 


**a ) r = 0.02 = (1/4) × rate of consumption of $\ce{NO2}$** 


Or : 


**b) r = 0.02 = (1/2) × rate of consumption of $\ce{NO2}$** 


Does the rate of the reaction changed when we multiply balanced reaction equation by integer? Why?


