1. **State the problem:** Trevor bought two items priced at 800 and 400 respectively, and he paid 12.5% VAT on the total price. We need to find the total amount Trevor paid including VAT. 2. **Calculate the total price before VAT:** $$\text{Total before VAT} = 800 + 400 = 1200$$ 3. **Calculate the VAT amount:** VAT rate is 12.5%, which as a decimal is 0.125. $$\text{VAT} = 1200 \times 0.125 = 150$$ 4. **Calculate the total amount paid including VAT:** $$\text{Total paid} = \text{Total before VAT} + \text{VAT} = 1200 + 150 = 1350$$ 5. **Interpretation:** Trevor paid 1350 in total for both items including VAT. **Final answer:** $$\boxed{1350}$$