Answer:
In general, a buffer system can be represented by writing a salt followed by slash and an acid or conjugate base followed by slash and an acid like salt/acid or conjugate base/acid. Thus, the sodium acetate-acetic acid buffer system can be written as
CH3COONa/ CH3COOH or CH3COO-/CH3COOH
Similarly, ammonia-ammonium chloride buffer system can be represented as
NH3 / NH4+
Note that NH4+ is an acid and NH3 is a conjugate base according to Lewry-Bronsted concept.