Answer
(a) $56mm$
(b) $-0.011$
Work Step by Step
(a) We know that
$d_i=(\frac{1}{f}-\frac{1}{d_{\circ}})^{-1}$
We plug in the known values to obtain:
$d_i=(\frac{1}{0.055}-\frac{1}{5.0})^{-1}$
$d_i=56mm$
(b) The magnification can be determined as
$m=-\frac{d_i}{d_{\circ}}$
We plug in the known values to obtain:
$m=-\frac{0.056}{5.0}$
$m=-0.011$