Please explain how to solve for the acceleration of the following. A train starts at rest and accelerates to 54 km/hr in 10 seconds.I know that you...

Acceleration is the rate of change of velocity. It is
expressed in the units (m/s)/s or m/s^2.

If the initial
velocity v0 and the final velocity vf after a duration of time d is given we can obtain
the acceleration during the interval d as (vf - v0)/d.

In
the problem, the train starts at rest and reaches a velocity 54 km/hr in 10
sec.

You have to convert all the values to the same units
before any calculations can be done. Ideally use the SI units. This gives the initial
velocity as 0 m/s. After 10 seconds the velocity is 54 km/hr or 54*1000/60*60 = 15
m/s

The acceleration of the train during the 10 seconds was
(15 - 0)/10 = 15 m/s^2.