Lens Maker equation and Geometrical equation

or a myopic swimmer with a prescription of -7.0 diopters, what should the radii of curvature of the lens surfaces be if the goggles are made from a high index plastic of n = 1.6? First, what is the radius of curvature of the outer surface (furthest from the eye)? If the surface is flat, enter ‘i’ for an infinite radius.