The temperature in Fargo was $\displaystyle-{{5}}^{\circ}\text{F}\usepackage{cmbright}\Huge\$ at 8 o'clock this morning. By 5 o'clock in the afternoon, the temperature had risen 15 degrees Fahrenheit. Find what the temperature was at 5 o'clock by filling in the missing number.

$\displaystyle-{{5}}^{\circ}\text{F}+{{15}}^{\circ}\text{F}={?}^{\circ}\text{F}\usepackage{cmbright}\Huge\$