Answer
(a) greater than
(b) $-351cm$
Work Step by Step
(a) We know that the second person's far point is $353cm$ and the image distance is $d_i=-351cm$, which is the focal length of the eye glasses. Thus, the magnitude of the focal length of the second person is greater than $351cm$.
(b) We know that
$\frac{1}{d_{\circ}}+\frac{1}{d_i}=\frac{1}{f}$
We plug in the known values to obtain:
$\frac{1}{\infty}+\frac{1}{-351cm}=\frac{1}{f}$
$\implies f=-351cm$
