Temperature affects the speed of sound. The speed (v) of sound near Earth's surface, in meters per second, is given by $\displaystyle{v}={20}\sqrt{{{t}+{273}}}\usepackage{cmbright}\Huge\$ , where t stands for the temperature of the air in degrees Celsius.

If the speed of sound is 320 meters per second, the temperature is _____ degrees Celsius.