Answer is: there are 14 atoms represented by the formula (NH₄)₂CO₃.
In ammonium carbonate there are two nitrogen atoms (because two ammonium cations), eight hydrogen atoms (because two ammonium cations), one carbon atom and three oxygen atoms:
2 · 1N + 2 · 4H + 1C + 3O = 14 atoms.
Ammonium carbonate is a salt.
