You may have thought this was a solution because substituting $\displaystyle{\left(-{1},-{1}\right)}\usepackage{cmbright}\Huge\$ into the inequality gives you 3 on the left side. However, the left side must be less than 3. That is, $\displaystyle{3}<{3}\usepackage{cmbright}\Huge\$ is a false statement, so $\displaystyle{\left(-{1},-{1}\right)}\usepackage{cmbright}\Huge\$ is not a solution to $\displaystyle{2}{y}-{5}{x}<{3}\usepackage{cmbright}\Huge\$ .