1. **State the problem:** Allegra drank 203 milliliters of water and then 157 milliliters of lemonade. We need to find the total amount of liquid she drank. 2. **Formula used:** To find the total amount of liquid, we add the amounts of water and lemonade: $$\text{Total liquid} = \text{Water} + \text{Lemonade}$$ 3. **Substitute the values:** $$\text{Total liquid} = 203 + 157$$ 4. **Calculate the sum:** $$203 + 157 = 360$$ 5. **Answer:** Allegra drank a total of 360 milliliters of liquid.