How do you convert degrees Celsius per mm Hg to just degrees Celsius?

You can't. Celsius per mmHg is a relationship of temperature to pressure. You can however solve for temperature if you have the value of pressure (e.g. if P= 10 mmHg and V/P = 2 ºC/mmHgthen V= (2 ºC/mmHg)(10 mmHg) = 20 ºC). If you have more information in the problem you might be referring to Gay-Lussac's Law, which compares two values of pressure and temperature to show the relationship (GL'sL: P1/T1 = P2/T2 ... but that would be pressure per unit volume). I'm not sure what you are looking for exactly, but you can't convert temp. to pressure (just like you can't convert feet to lbs.).