Answer
$491.69^{\mathrm{o}}\mathrm{R}$
Work Step by Step
Triple point: $\mathrm{T}=273.15 \mathrm{K}.$
For temperature intervals, $\displaystyle \frac{\Delta T_{\mathrm{C}}}{\Delta T_{\mathrm{F}}}=\frac{5}{9}$, and $\Delta T_{\mathrm{K}} =\Delta T_{\mathrm{C}}$
and, we are given $\Delta T_{R} =\Delta T_{\mathrm{F}}$
Therefore, $\displaystyle \frac{\Delta T_{K}}{\Delta T_{R}}=\frac{5}{9}$, so
$\displaystyle \Delta T_{R}=\frac{9}{5}\Delta T_{K}=\frac{9}{5}(273.15)=491.69^{\mathrm{o}}\mathrm{R}$
