1. The problem asks for the resulting percentage of salt concentration when 1.5L of a 30% salt solution is mixed with 0.75L of pure water. 2. The formula to find the new concentration after mixing is: $$\text{New concentration} = \frac{\text{Amount of salt}}{\text{Total volume}} \times 100\%$$ 3. Calculate the amount of salt in the original solution: $$\text{Salt} = 1.5 \text{ L} \times 0.30 = 0.45 \text{ L of salt}$$ 4. Calculate the total volume after mixing: $$\text{Total volume} = 1.5 \text{ L} + 0.75 \text{ L} = 2.25 \text{ L}$$ 5. Calculate the new concentration: $$\text{New concentration} = \frac{0.45}{2.25} \times 100 = 20\%$$ 6. Therefore, the resulting salt concentration is 20.