Answer:
Slope = 50
Explanation:
Given the two points (40, 2,000) and (60, 3,000) on the line of the function.
[tex]\begin{gathered} \text{Slope}=\frac{Change\text{ in y-axis}}{Change\text{ in x-axis}} \\ =\frac{3000-2000}{60-40} \\ =\frac{1000}{20} \\ =50 \end{gathered}[/tex]The slope is 50 which means that the amount of water in the reservoir is increasing at a rate of 50 cubic feet each hour.