Answer
(a) 1600 mm should be the objective and 32 mm as eyepiece.
(b) $50X$
Work Step by Step
(a) We know that the lens having the longer focal length (1600 mm) should be used as the objective and the lens having 32 mm should be used as the eyepiece.
(b) We can find the magnification as
$M=\frac{f_{objective}}{f_{eyepiece}}$
We plug in the known values to obtain:
$M=\frac{1600}{32}=50X$
