A point object is placed at a distance R from the convex surface AB of a glass of radius of

A point object is placed at a distance R from the convex surface AB of a glass of radius of curvature `R_(1)=R` and refractive index `n=1.5`. The second curved surface CD is silvered and its radius of curvature is `R_(2)=R` if the distance of the final image formed is `alphaR` from the surface AB rhen find `alpha`?