1. **State the problem:** Elsie's Lemonade uses 30 milliliters of lemon juice and twice as much syrup for each glass. We need to find the total amount of syrup needed for 75 glasses, expressed in liters. 2. **Identify the formula and important rules:** - Amount of syrup per glass = 2 \times amount of lemon juice per glass. - Total syrup = syrup per glass \times number of glasses. - Convert milliliters to liters: 1000 milliliters = 1 liter. 3. **Calculate syrup per glass:** $$\text{syrup per glass} = 2 \times 30 = 60 \text{ milliliters}$$ 4. **Calculate total syrup for 75 glasses:** $$\text{total syrup} = 60 \times 75 = 4500 \text{ milliliters}$$ 5. **Convert total syrup to liters:** $$\text{total syrup in liters} = \frac{4500}{1000} = 4.5 \text{ liters}$$ 6. **Final answer:** The total amount of syrup needed for 75 glasses is **4.5 liters**.