TeX source:

Kc = \frac{c(NH_3)^2}{c(H_2)^3 \bullet c(N_2)} = \frac{(3 \frac{mol}{l})^2}{(5,5 \frac{mol}{l})^3 \bullet (10,5\frac{mol}{l})} = 0,0052 \frac{l^2}{mol2}