Foreign investment appraisal – Example 4 James Plc – Discounted cash flow

In this example – when calculating the tax payable – I noticed you split it into 2 parts – tax payable in oblivia (20%) and extra UK tax (5% after converting from Euros to £s). This is due to the double taxation treaty.

While I understand this principle – could we not cut out a step and simple tax from the outset 25% which would leave the same net figure after converting to £s?

Would we lose marks by doing this?

Thanks