Answer:
y = -2000x + 30,000 is the correct answer.
Explanation:
For slope intercept equation we first determine the intercept on the axis.
The intercept is a constant value, c, in the slope intercept equation.
In this case, the constant value is 30,000.
Our height, y, is directly proportional to minute,x, taken to descend.
y = mx + c
M is the slope/ gradient which is -2000 since the airplane is descending.
Since the plane descends 2000 feet per minute, its height after 1 minute should be:-
y = -2000(1) + 30,000
y = 28,000
This calculation confirms our above answer.