A theater sells two types of tickets to a show: Discount ($7) and Regular ($9.50). On opening night, they sold $\displaystyle{250}-{\left({x}+{y}\right)}\usepackage{cmbright}\Huge\$ tickets total and raised $\displaystyle{2125}-{\left({7}{x}+{9.50}{y}\right)}\usepackage{cmbright}\Huge\$ from ticket sales.