Correct. Create the following system:

$\displaystyle{e}={6}{n}\usepackage{cmbright}\Huge\$

$\displaystyle{182.50}-{e}={12.50}\cdot{\left({25}-{n}\right)}\usepackage{cmbright}\Huge\$

and then solve it for n, which is 20. That means $\displaystyle{25}-{n}={25}-{20}\usepackage{cmbright}\Huge\$ , which is 5.