How Do You Calculate Acceleration from Zero to 25 m/s in 30 Seconds?

[HighSchooler]

Homework Statement

A train moves from rest to a speed of 25 m/s in 30.0 seconds. What is the magnitude of its acceleration?

Homework Equations

The Attempt at a Solution

I don't know how to find the magnitude

 

[haruspex]

Is it just the word magnitude that's bothering you? That simply means the size of the acceleration, not worrying what direction it's in.
Given a change in speed and the time it takes, do you know how to calculate the acceleration?