At $500^{\circ} \mathrm{C}, K$ for the formation of ammonia from nitrogen and hydrogen gases is $1.5 \times 10^{-5}$
$$
\mathrm{N}_{2}(g)+3 \mathrm{H}_{2}(g) \rightleftharpoons 2 \mathrm{NH}_{3}(g)
$$
Calculate the equilibrium partial pressure of hydrogen if the equilibrium partial pressures of ammonia and nitrogen are 0.015 atm and 1.2 atm, respectively.