A magnifying glass is a single convex lens with a focal length of = +14.0 cm.

Question:

A magnifying glass is a single convex lens with a focal length of ƒ = +14.0 cm.
(a) What is the angular magnification when this lens forms a (virtual) image at -∞? How far from the object should the lens be held?
(b) What is the angular magnification when this lens forms a (virtual) image at the person's near point (assumed to be 25 cm)? How far from the object should the lens be held in this case?