The two surfaces of an equiconvex spherical lens have the same curvature. An object $5$ cm tall is placed on the central axis at $75$ cm in front of the lens. The $[$real$]$ image of the object formed on a wall is $8$ cm tall. If the refractive index of the lens is $1\mathrm{.}5,$ find the radii of curvature for this lens.