What is the rate of deceleration of a 1400-kg SUV that is going 75.0 km/h and then slows to 25.0 km/h in 8.20 s?

Figured it out,
Don't worry about the mass, just solve for Deceleration. which is deltavelocity/delta time

>>Subtract First(75 - 25) = 50 km/hr*(1hr/3600 sec) = 50/3600 = 0.01389 km/s. <<Dont Forget the conversion to sec

>>>Then delta velocity/ delta time = 0.01389/8.2 = 0.001694 km/s^2 = 1.7 m/s^2