Start by using the addition as a sign and use multiplying
Answer:

Generally given that the electric field is negative it mean that its direction is opposite to that of the force
Explanation:
From the question we are told that
The charge on the small object is 
The force is 
Generally the magnitude of the electric field is mathematically represented as

=> 
=> 
Generally given that the electric field is negative it mean that its direction is opposite to that of the force
initial velocity (u)=0m/s
final velocity (v)=10m/s
time( t)=5s
acceleration (a)=v-u÷t
acceleration (a)=10-0÷5
acceleration (a)=10÷5
acceleration (a)=2
therefore acceleration (a)=2m/s