A single-phase, 3-kVA, 220:110-V, 60-Hz transformer has a high-voltage winding resistance of 0.3 Ω, a low-voltage winding resistance of 0.06 Ω, a leakage reactance of 0.8 Ω on its high voltage side, and a leakage reactance of 0.2 Ω on its low-voltage side. The core loss at rated voltage is 45 W, and the copper loss at rated load is 100 W. Neglect the exciting current of the transformer. Find the per-unit voltage regulation when the transformer is supplying full load at 110 V and 0.9 lagging power factor.