I am having trouble trying to figure out which formula to use for this problem and how to set it up. I?

The driver of a truck slams on the brakes when he sees a tree blocking the road. The truck slows down uniformly with acceleration -5.3 m/s2 for 4.20 s, making skid marks 67.1 m long that end at the tree. With what speed does the truck then strike the tree?





If someone could work this out or help me get started that would be amazing.I am having trouble trying to figure out which formula to use for this problem and how to set it up. I?
d = 67.1 m


a = -5.3 m/s^2


t =4.2 s





d = V0 * t + 0.5*a*t^2


from this equation we can find the inital speed V0


V0 = (d - 0.5*a*t^2) / t = d/t - 0.5*a*t





Once V0 is known, we can find the final speed:


V = V0 + at = d/t - 0.5*a*t + a*t = d/t + 0.5*a*t


V= 67.1/4.2 -0.5*5.3*4.2 = 4.85 m/s

freckles