Am I missing info for this Ideal Gas Equation?

Given that there are 3L of NH3, how many Liters of N2 are needed?
PV=nRT (equation to be used)
R=0.08206 Latm/molK
V= 3L of NH3
V=?L of N2
What is ‘n’ and how do I find it? And then how do I find the Volume for the amount of N2 needed to create 3L of NH3?