Use equations to explain how a buffer system, such as hno2:no2, reacts with h3o and oh?

Answer 1

HNO2/NO2^- system.
With H3O^+ the NO2^- uses that as
H3O^+ + NO2^- ==> HNO2 + H2O

With OH^- the HNO2 uses that as
HNO2 + OH^- ==> NO2^- + H2O