Formula for New Temperature Scale?

Suppose a new temperature scale has been devised on which the melting point of ethanol (-117.3C) and the boiling point of ethanol (78.3C) are as 0S and 100S, respectively, where S is th...e symbol for the new temperature scale. Derive an equation relating a reading on this scale to a reading on the Celsius scale. What would this thermometer read at 25C?