Question

3 known charges and 1 unknown create a given electric field. Find the value of the magnitude of the unknown charge

An unknown positive point charge is placed at x = -0.36 m, y = 0 m, a charge of -4.8 micro-coulombs is placed at x = 0 m, y = -0.23 m, a charge of +2.4 micro-coulombs is placed at x = +0.37 m, y = -0.2 m, and charge of +4.8 micro-coulombs is placed at x = 0 m, y = +0.23 m. If the total electric field due to all four charges at the origin is 3.9 x 106 N/C (the x component of the total electric field is positive), what is value of the magnitude of the unknown charge in micro-coulombs? If negative, include a negative sign.