A single-phase step-down transformer is rated $15 \mathrm{MVA}, 66 \mathrm{kV} / 11.5 \mathrm{kV}$. With the $11.5 \mathrm{kV}$ winding short-circuited, rated current flows when the voltage applied to the primary is $5.5 \mathrm{kV}$. The power input is read as $100 \mathrm{~kW}$. Determine $R_{\mathrm{eq} 1}$ and $X_{\mathrm{eq} 1}$ in ohms referred to the high-voltage winding.