If the speed is constant, there is no acceleration. No acceleration, no force.
To find the rate of change, also known as the slope, we can use the slope formula with these two given points.
Point 1: (20, 25)
Point 2: (50, 40)
(40 - 25) / (50 - 20)
15 / 30
0.5
The rate of change of this function is $0.50 / lb.
Hope this helps!! :)
Something to the third power would mean you are cubing something... So should it be B?