Problem in physic of electric charge

[lovelycecila]

consider a circular clock face of radius= 50cm.a charge of 3nC is placed at the 3 o'clockpoint (a distane of 50cm from the center of the face). a charge of 6nC is placed at the 6 o'clockpoint.9nC is placed at the 9 o'clockpoint and 12nC is placed at the 12 o'clockpoint.
what is the electric field in the centre of the clock

 

[Defennder]

Well, the net electric field is due to the vector superposition of all the electric charges. So how would you use that to do this question?