Moving uniformly along the Ox axis during the time interval delta t = 3.5 s with an initial speed, the projection

Moving uniformly along the Ox axis during the time interval delta t = 3.5 s with an initial speed, the projection of which on this axis Vox = 4.0 m / s, the body made a displacement, the projection of which delta tx = 63 m. What is the projection of acceleration a ^ x body?

Equally accelerated movement:
Sx (displacement) = Voht + at ^ 2/2
at ^ 2 = 2 * (Sx-Voxt)
a = 2 * (Sx-Voxt) / t ^ 2
a = 2 * (63m-14m) / 16c ^ 2 = 49/8 (m / s ^ 2) = 6.125m / s ^ 2
Answer: a = 6.125m / c ^ 2