Molecular Diffusion in Gas : Equimolar Counter Diffusion

Equimolar concentration case concludes that the diffusivity of A through B is equivalent to the diffusivity of B through A. How do we derive to that such conclusion is explained here, starting with writing assumptions, translating them into equations and finally to conclude the findings.

[@yassineaguelmam8674]

Thank you

[@abdallaelshennawi4767]

it is very good but why you did not continues