A reservoir's water level decreased by 20% over the summer due to evaporation. If the water level is currently at 120 million liters, how much water was there initially?

• A. 24 million liters
• B. 150 million liters
• C. 96 million liters
• D. 30 million liters

Answer: (B)

Verified step by step guidance

1. Identify the given information: the water level decreased by 20%, and the current water level is 120 million liters.
2. Understand that a 20% decrease means the current water level is 80% (100% - 20%) of the initial water level.
3. Express the relationship between the current water level and the initial water level using the equation: \(\text{Current Level} = 0.80 \times \text{Initial Level}\).
4. Rearrange the equation to solve for the initial water level: \(\text{Initial Level} = \frac{\text{Current Level}}{0.80}\).
5. Substitute the known current water level (120 million liters) into the equation to find the initial water level.