an object travels 219 meters with acceleration 6.43 m/s^2 over an interval of 2.86 seconds. What are Vi and Vf.

Vf = Vi + a t

Vf = Vi +6.43 t
where t = 2.86

d = Vi t +(1/2) a t^2
219 = Vi t + 3.215 t^2
where t = 2.86
solve for Vi
then go back and get Vf