The change in velocity can be calculated by subtracting the final velocity from the initial velocity. In this case, the car decelerates from 25 m/s to 10 m/s. Therefore, the change in velocity is:
Change in velocity = Final velocity - Initial velocity
Change in velocity = 10 m/s - 25 m/s
Change in velocity = -15 m/s
The negative sign indicates that the velocity is decreasing or the car is decelerating. Therefore, the change in velocity is -15 m/s.