Voltage drop across a transformer

I have not worked in per unit since school. I am seeking help with a project trying to find the voltage drop across a transformer with 7% impedance versus a transformer at 8.5% impedance. The high side bus is 115kV and low side is a 34.5kV bus. 6-100MVA transformers are in parallel between theses buses and a load of 370 MW on the 34.5kV bus @ 0.95 pf. Need to find the voltage drop difference in modeling this with the different transformer impedances. The 115kV bus is at 1.0361 and the low side 34.5 bus is at 1.0395. Seeking help in working out how to solve this