A 7.0-μC point charge and a 9.0-μC point charge are initially extremely far apart. How much work does it take to bring the 7.0-μC point charge to the point x = 3.0 mm, y = 0.0 mm, and the 9.0-μC point charge to the point x = -3.0 mm, y = 0.0 mm? (k = 1/4πε0 = 9.0 × 109 N ∙ m2/C2)