Incorrect. The information gives you two equations:

$\displaystyle{x}-{y}={58}\usepackage{cmbright}\Huge\$ and $\displaystyle\frac{{{x}+{y}}}{{2}}={323}\usepackage{cmbright}\Huge\$

Multiply the second equation by 2 and add this to the first equation. Solve for x. Substitute into any equation and solve for y. The correct answer is 294.