Two charges are placed on the y axis. One charge of +3.6 micro-coulombs is placed at y +3.8 m, and another charge of +13.3 micro-coulombs is placed at y = -4.8 m. If a third charge of -9 micro-coulombs is placed between them, where on the y axis (i.e. y = ______) is the total for electric force on this charge equal to zero? Answer in meters.