We can express the location of the passener as a point (t, h)
where t is the time passes in minutes
and h is the height or elevation in feet
The first point is when time is 0 min and the starting elevation is 6559 feet.
So this will be the first point (0, 6559)
The next point is after 1 minute which has an elevation of 6814 feet.
So the second point will be (1, 6814)
Note that the equation of the line formed between two points can be determine using two-point formula.

where x1, y1 are the coordinates of the first point
and x2 y2 are the coordinates of the second point
Substitute the given values to the formula :

Now replace the variables, x to t, and y to h
a. The linear function will be :

b. the slope and the vertical intercept :
Note that if the line is in the form of :

m is the slope and b is the y-intercept or vertical intercept.
From the linear function we have.
the slope is 255
and the vertical intercept is 6559
The slope of 255 means that the elevation is increasing at a rate of 255 feet per minute
and the vertical intercept means that this is the starting elevation at time = 0.
The starting elevation is 6559 feet