Answer:
The slope is -9/4 or -2.25.
Explanation:
To find the slope (S) we need to use the following equation:

Where:
y₂: is the final height = 11 feet
y₁: is the initial heoght = 20 feet
x₂: is the final position is the horizontal direction = 4 feet
x₁: is the initial position = 0 (origin)
Therefore, the slope is -9/4 or -2.25.
I hope it helps you!