A student is examining an ant with a magnifying glass.The student's near point

A student is examining an ant with a magnifying glass. The student’s near point is N = 19 cm from the eye and the magnifying glass has a focal length of f = 9.9 cm.

a) Write an expression for the angular magnification that the student observes when the image distance of the ant is -56 cm.
b) Numerically, what is this angular magnification?
c) Write an expression for the angular magnification when the ant is placed exactly at the focal point of the lens.
d) Numerically, what is this angular magnification?