A three-phase transformer is rated $500 \mathrm{MVA}, 220 \mathrm{Y} / 22 \Delta \mathrm{kV}$. The wye-equivalent short-circuit impedance, considered equal to the leakage reactance, measured on the low-voltage side is $0.1 \Omega$. Compute the per-unit reactance of the transformer. In a system in which the base on the high-voltage side of the transformer is 100 MVA, 230 $\mathrm{kV}$, what value of the per-unit reactance should be used to represent this transformer?