Correct. Add the equations to get: $\displaystyle{2}{y}={2}\usepackage{cmbright}\Huge\$

Divide both sides by 2: $\displaystyle{y}={1}\usepackage{cmbright}\Huge\$

Substitute $\displaystyle{y}={1}\usepackage{cmbright}\Huge\$ into the first equation: $\displaystyle{5}{x}+{1}={51}\usepackage{cmbright}\Huge\$ , so $\displaystyle{5}{x}={50}\usepackage{cmbright}\Huge\$ and $\displaystyle{x}={10}\usepackage{cmbright}\Huge\$