Help with physics question?

A very small charged block with a mass of 2.90 g is placed on an insulated, frictionless plane inclined at an angle of 17.0� with respect to the horizontal as shown in the figure below. The block does not slide down the plane because of a 430 N/C uniform electric field that points parallel to the surface downward along the plane. What is the sign and magnitude of the charge on the block?