Correct. The information leads to the equation $\displaystyle{x}{\left({25}-{x}\right)}={126}\usepackage{cmbright}\Huge\$ . This becomes $\displaystyle{25}{x}-{{x}}^{{2}}={126}\usepackage{cmbright}\Huge\$ or $\displaystyle{0}={{x}}^{{2}}-{25}{x}+{126}\usepackage{cmbright}\Huge\$ . Use the Quadratic Formula:

$\displaystyle{x}=\frac{{-{\left(-{25}\right)}\pm\sqrt{{{{\left(-{25}\right)}}^{{2}}-{4}\cdot{1}\cdot{126}}}}}{{{2}\cdot{1}}}=\frac{{{25}\pm\sqrt{{{625}-{504}}}}}{{2}}=\frac{{{25}\pm\sqrt{{121}}}}{{2}}=\frac{{{25}\pm{11}}}{{2}}\usepackage{cmbright}\Huge\$

So $\displaystyle{x}={18}\usepackage{cmbright}\Huge\$ or 7. The baker charged $7 for one pie.