In Newton's law of cooling $\frac{\mathrm{d\theta }}{\mathrm{dt}}=-\mathrm{K}(\mathrm{\theta }-{\mathrm{\theta }}_0)$. The proportionality constant K is K₁ and K₂ for two substances A and B having mass m₁ and m₂, surface area A₁ and A₂, specific heat S₁ and S₂, emissivity e₁ and e₂ respectively, it is given that $\frac{{\mathrm{e}}_1}{{\mathrm{e}}_2}=1,\frac{{\mathrm{A}}_1}{{\mathrm{A}}_2}=1,\frac{{\mathrm{m}}_1}{{\mathrm{m}}_2}=2,\frac{{\mathrm{S}}_1}{{\mathrm{S}}_2}=\frac{1}{3},$, while surrounding temperature remain constant. If $\frac{{\mathrm{K}}_1}{{\mathrm{K}}_2}=\frac{12}{\mathrm{X}}$ then X is :