At a distance of 0.3m along the x-axis from the origin, there is a charge of 6.00nC, and at a distance of -0.1m along the y-axis from the origin, there is a charge of -3.00nC. Additionally, there is a charge of 5.00nC at the origin. 

(a) Determine the electric field vector created at the origin by charges of 6.00 nC and -3.00 nC. 

(b) Find the force vector acting on a charge of 5.00 nC.