Intro to Physics: Speed & Acceleration

A train travelling at 10 m/s accelerates to 20 m/s in 5 seconds
i) What is its acceleration
ii) What will its speed be after another three seconds if it continues to accelerate at the same rate?

I know the formula is
a = v-u / t

So please show me, step by step, the working out using the formula :)

V=final velocity
u=initial velocity
a=acceleration
t=time
as you know a=(v-u)/t
after 5 second acceleration=(20-10)/5
=2 m/s2

2.
in second case take u=20m/s
t=3sec
v=u+at
v=20+2*3
v=26m/s
2.

acceleration is change in velocity by time taken.
(20-10)/5=2m/s.s
after 3 seconds,
v= u +at
=20+6=26m/s

Gffvc