## Basic College Mathematics (9th Edition)

$\frac{25}{100}=\frac{80}{n}$ (We are asked not to solve for $n$, so we stop here.)
We know that 25% of the emails is 80. Thus, to find out the total number of emails, we set up a proportion: $\frac{25}{100}=\frac{80}{n}$ Where $n$ is the total number of emails. (We are asked not to solve for $n$, so we stop here.)