Equilibrium constant (k)?

it says the expression for the quilibrium constant K for the reactions below

N2(g) + 3H2(g) ↔ 2NH3(g)

Idk what to do?!?!?

equilibrium expression is set up as
K = [products] / [reactants] and where coefficients become powers.

Keq = [NH3]^2 / ( [N2] x [H2]^3 )