If we take v=u+at and our given values are:
v=final velocity 20m/s
u=initial velocity 15m/s
a=acceleration
t=time 5sec
we plug those into our equation:
20m/s=15m/s+a(5s)
now we just rearrange to solve for acceleration.
(5m/s)/(5s)=a
a=1m/s^2
hope this helps!
PLEASE MARK BRAINLEIST