The electric field at the point x = 5.00 cm and y = 0 points in the positive x direction with a magnitude of 15.0 N/C. At the point x = 20.0 cm and y = 0 the electric field points in the positive x direction with a magnitude of 30.0 N/C. Assume that this electric field is produced by a single, point charge. (a) Find the location of the point charge. (b) Find the sign and magnitude of its charge.