Problem 5.58

At what thickness will a thick convex-concave glass lens in air (a) serve as a telescope provided the curvature radius of its convex surface is $\Delta R=1.5 \mathrm{~cm}$ greater than that of its concave surface? (b) have the optical power equal to $-1.0 \mathrm{D}$ if the curvature radii of its convex and concave surfaces are equal to 10.0 and $7.5 \mathrm{~cm}$ respectively?