The graph shows the altitude, a, of a plane, in feet, after t minutes. What is the rate of ascent of the airplane?
A.125 feet per minute
B.120 feet per minute
C.150 feet per minute
D.175 feet per minute

The rate of ascent is also known as the slope. To find the slope, we will follow the steps below.

Step 1) Choose two points on the line

Point 1: (4, 500)

Point 2: (8, 1000)

Step 2) Use the slope formula to find the slope

m = (y2 - y1) / (x2 - x1)

m = (1000 - 500) / (8 - 4)

m = 500 / 4

m = 125 feet per minute

Hope this helps! :)