A Double Convex Lens Has Faces with Radii of Magnitudes

Short Answer

A double convex lens has faces with radii of magnitudes 18.0 cm and 20.0 cm. When an
object is placed 24.0 cm in front of the lens, a real image is formed 32.0 cm from the lens.
(a) What is the focal length of this lens?
(b) What is the index of refraction of the material from which the lens is made?