The velocity of the car at various times is given as:
Velocity at 15 seconds = f(15) = 45
Velocity at 22 seconds = f(15) = 66
Velocity at 29 seconds = f(15) = 87
Velocity at 36 seconds = f(15) = 108
We are to find the average rate of change of f(x) from x=15 to x=29, which can be written as:

Therefore, the average rate of change of function from x=15 to x=29 is 3. Since the rate of change of velocity gives us acceleration, so the acceleration of the car between 15 to 29 seconds will be 3 m/s²