Which of the following formulas best conveys the equilibrium expression for the following reaction?
$$2NOBr(g) \rightleftharpoons 2NO(g) + Br_2(g)$$
$$ \frac{[NO]^2[Br_2]}{[NOBr]^2} $$
$$ \frac{[NOBr]}{[NO][Br_2]} $$
$$ \frac{[NO]^2[Br_2]}{[NOBr]^2} $$
$$ \frac{[NO][Br_2]}{[NOBr]^2} $$
$$ \frac{[NOBr]}{[NO][Br_2]} $$