$Kc = [NO_2]^2/ ([N2][O2]^2) $
The Kc is measured at the equilibrum
$8.3 * 10^-10 = x^2/([N_2][x]^2)$
Conc of $N_2 "when" NO_2 = O_2$ = 1204819277.108434mol
$8.3 * 10^-10 = (5x^2)/(N_2 * x^2)$
Let's solve for $N_2$.
$8.3(10^−10)= (5x)^2 /(x^2N_2)$
Step 1: Multiply both sides by $N_2$
$0N_2=25$
Step 2: Divide both sides by 0.
$(0N_2)/0 = 25/0$
$N_2=30120481927.710842mol$
Answer:
$N_2=30120481927.710842mol$