Given the function below

a) This is the equation of the line into slope intercept form
The slope(m) is equal to

The slope is negative, because is decreasing.
Therefore, the elevation is decreasing by 80 feet each second.
b) The E-intercept is the value of E when the value of t is equal to zero
Substitute t = 0 into the equation

Therefore, the equation tells us that Terry started at an elevation of 3,500ft.