At what temperature (in Kelvin) will the  kinetic energy of 0.3 mole of ‘He’ be the same that of 0.4 mole of argon at 400 K?

Given,
number of mole of He, ${\mathrm{n}}_1=0.3\mathrm{mol}$
number of mole of Ar, ${\mathrm{n}}_2=0.4\mathrm{mol}$
Temperature, ${\mathrm{T}}_{\text{2}}=400\mathrm{K}$
Temperature,  ${\mathrm{T}}_{\text{1}}=?$
 $\mathrm{KE}=\frac{3}{2}\mathrm{nRT}$
Where, R is the gas constant
K.E. is the kinetic energy 
 

$\Rightarrow {\left(\frac{3}{2}\times 0.3\times \mathrm{R}\times \mathrm{T}\right)}_{\text{Helium}}={\left(\frac{3}{2}\times 0.4\times \mathrm{R}\times 400\right)}_{\text{Argon}}$

$\therefore \mathrm{T}=533.333\hspace{0.17em}\mathrm{K}$