Two mercury-glass thermometer are labelled T and D respectively.On T scale, at 1 atmosphere, ice melts at -10T and pure water boils at 80T. On the D scale ice melts at 20D and pure water boils at 100D at 1 atmospheric pressure.

(a) Derive an equation relating the two temperature scales
(b) What would the temperature on D reading if on T it reads 50T?