Show the validity of the following equation based on Fick's law:

\[\begin{equation*}abla x_{\mathrm{A}}=\frac{x_{\mathrm{A}} N_{\mathrm{B}}-x_{\mathrm{B}} N_{\mathrm{A}}}{C D_{\mathrm{AB}}} \tag{9.59}\end{equation*}\]

Show that the following equation holds as well:

\[\begin{equation*}abla x_{\mathrm{A}}=\frac{x_{\mathrm{A}} J_{\mathrm{B}}-x_{\mathrm{B}} J_{\mathrm{A}}}{C D_{\mathrm{AB}}} \tag{9.60}\end{equation*}\]

Verify that the Stefan-Maxwell equation reduces to these equations when applied to a binary mixture.