Please help me with these questions:

3. Calculate the electrical potential energy in Joules, of two particles (3.033x10^0) nC and (-8.68x10^0) nC, which are a distance (6.6407x10^0) m apart.

4. Two particles q1 = (1.45x10^0) nC and (1.9760x10^0) nC are initially (8.574x10^0) metres apart, and then move to (1.910x10^1) metres apart. Calculate the change in potential energy in Joules