Correct. The pool will have $\displaystyle{2.5}{x}\usepackage{cmbright}\Huge\$ gallons in $\displaystyle{x}\usepackage{cmbright}\Huge\$ minutes, so it will be half full when $\displaystyle{2.5}{x}={25}\usepackage{cmbright}\Huge\$ , which happens when $\displaystyle{x}=\frac{{{25}}}{{{2.5}}}={10}.\usepackage{cmbright}\Huge\$