Can someone help me solve this problem?

2.1 As in the figure, the electric field is 15.0 N/C: m (a) A charge q = +2.0 nC moves to the right for 5.0 m, what is the electric potential energy change? [ Answer: - 1.5 x 10-7 J] (b) If a charge q = +2.0 nC moves to the left for 5.0 m, what is the electric potential energy change? [Answer: +1.5 x 10-7 J] (c) If a charge q = -2.0 nC moves to the right for 5.0 m, what is the electric potential energy change? [Answer: +1.5 x 10-7 J] (d) If a charge q = -2.0 nC moves to the left for 5.0 m, What is the electric potential energy change? [Answer: -1.5 x 10-7 J]