Parallel transformers: PE Power Electric Power Devices practice question

A 69–12.47 kV distribution substation has two transformers connected in parallel on both sides:

• T1: 20 MVA, impedance 8.0% on its own base
• T2: 15 MVA, impedance 7.0% on its own base

Both have the same turns ratio and the same X/R ratio. The utility wants to know how much total load the substation can carry without loading either transformer above its nameplate rating.

The maximum total load is most nearly: