Short line voltage regulation: PE Power Transmission and Distribution practice question

A 69 kV, 60 Hz subtransmission line 15 mi long feeds an industrial substation. The per-phase series impedance of the line is $0.15 + j0.72\ \Omega/\text{mi}$, and its shunt capacitance can be neglected. At full load the substation draws 30 MW at 0.85 power factor lagging with 66 kV line-to-line at the receiving end. The voltage regulation of the line at this load is most nearly: