Electric Potential Energy of Point Charges

Three point charges are positioned in the xy-plane: $q_1 = 2.0\ \mu \mathrm{C}$ at (0, 0), $q_2 = -3.0\ \mu \mathrm{C}$ at (3.0 m, 0), and $q_3 = 4.0\ \mu \mathrm{C}$ at (0, 4.0 m). What is the total electric potential energy of this system of charges? Use $k = 8.99 \times 10^9\ \mathrm{N \cdot m^2/C^2}$.