The rate of evaporation of component A divided by the rate of evaporation of component $B$ in a mixture containing $\mathrm{A}$ moles of $\mathrm{A}$ and $\mathrm{B}$ moles of $\mathrm{B}$ is directly proportional to $\mathrm{A} / \mathrm{B}$. If a mixture originally contained 5 moles of $A$ and 3 moles of $B$ and the rate of evaporation of $A$ is 5 moles/h and of $\mathrm{B}$ is $2.6 \mathrm{moles} / \mathrm{h}$, derive an equation for the concentration of A relative to that of $\mathrm{B}$.