1. **State the problem:** We are given that a 25 cent return deposit represents 6.25% of the total cost of a 2 litre soft drink. We need to find the total cost of the soft drink. 2. **Formula used:** To find the total cost when a part and its percentage are known, use the formula: $$\text{Total Cost} = \frac{\text{Part}}{\text{Percentage}}$$ where the percentage is expressed as a decimal. 3. **Convert percentage to decimal:** $$6.25\% = \frac{6.25}{100} = 0.0625$$ 4. **Calculate total cost:** $$\text{Total Cost} = \frac{0.25}{0.0625}$$ 5. **Simplify the fraction:** $$\frac{0.25}{0.0625} = \frac{\cancel{0.25}}{\cancel{0.0625}} = 4$$ 6. **Interpretation:** The total cost of the soft drink is 4 (units of currency). **Final answer:** $$\boxed{4}$$