Convert from degree Rankine to degree Reaumur

Unit Definition (degree Rankine)
The degree Rankine is a traditional unit of absolute temperature. 1 °Rankine represents the same temperature difference as 1 °Fahrenheit, but the zero point of the scale is set at absolute zero. This means the Rankine temperature is 459.67° plus the Fahrenheit temperature. 1 °Rankine is equal to exactly 5/9 kelvin. The unit is named for the British physicist and engineer William Rankine (1820-1872).

Unit Definition (degree Reaumur)
The degree Réaumur is a unit of temperature formerly used in continental Europe. The Réaumur temperature scale is named for the French scientist René-Antoine Ferchault de Réaumur (1683-1757). It is similar to the Celsius scale in having its zero point at the freezing temperature of water, but the interval between the freezing and boiling temperatures of water equals 80 °r instead of 100 °C. Therefore, 1 °r equals 1.25 °C or 2.25 °F.