Let's read the following and attempt to answer to the parts (a), (b), (c).
In this question, it measures the amount of water captured by the 4 reservoirs based on the rise & fall of the water levels. What assumption does to question make in order for your answers to be valid?
Source: S1 Maths workbook
In your notebook
Let's describe the change of the water level using number lines - one line for each reservoir.