There are two point charges on the y-axis. One has a charge of -3.0 μC and is located 4.0 cm above the origin. The other has a charge of +5.0 μC and is located 7.0 cm above the origin. A third point charge with charge +4.0 μC is placed on the x-axis at a distance of 6.0 cm in the positive direction of the x-axis from the origin. What is the potential energy of this group of charges?