Two point charges, Q1 = -6.7μC and Q2 = 1.8μC are located between two oppositely charged parallel

Question:

Two point charges, Q1 = -6.7μC and Q2 = 1.8μC are located between two oppositely charged parallel plates, as shown in Fig. 16-65. The two charges are separated by a distance of x = 0.34. Assume the electric field produced by the charged plates in uniform and equal to E = 73,000N/C. Calculate the net electrostatic force on Q1 and give its direction.