How to calculate acceleration from distance traveled and two instantaneous velocities

Question

A train started from rest and moved with constant acceleration, At one time it was travelling at 30m/s and 160metres further on it was travelling at 50m/s,

how do I find:

1. Acceleration

2.time required to travel the 160m mentioned

Answer 1

2. time required to travel the 160 m

Δx = .5(vi + vf) * Δt

Δx = 160 m

vi = 30 m/s

vf = 50 m/s

Δt = ?

160 = .5(30 + 50) * Δt

160 = 40 * Δt

Δt = 160 / 40 = 4 s

1. acceleration over the 160 m

vf = vi + a *Δt

50 = 30 + a * 4

a = (50 - 30) / 4 = 5 m/s/s