A braking train can decelerate at 0.4m/s^2. If the train is traveling at 160km/hr and needs to plan to stop at a pick-up area. How far in advance does it need to apply the brakes?

Question

A braking train can decelerate at 0.4m/s^2. If the train is traveling at 160km/hr and needs to plan to stop at a pick-up area. How far in advance does it need to apply the brakes? 
I know I need to convert the 160km/hr into m/s, which I did, it's 44.4m/s, but I'm super confused on how to solve it from there. 
Thanks for the help!

R_scott · Answer

divide the velocity by the deceleration to find the stopping time (44.4 m/s) / (0.4 m/s^2) = ? s