Given in the question:
a.) Function f gives the vertical distance of each town from sea level.
This means that f is directly equivalent to the elevation e.
Let's complete the table.
e 180 12.1 5.4 0 -5.4 -36 -180
f(e) 180 12.1 5.4 0 -5.4 -36 -180
Negative elevation means the towns are below sea level.