Answer
$d_{id}=10.0cm$
$m=-1$
Work Step by Step
$f_c=20.0cm$
$f_d=-10.0cm$
$d=25cm$
$d_{oc}=60.0cm$
$d_{ic}=\frac{1}{\frac{1}{f}-\frac{1}{d_{oc}}}=\frac{1}{\frac{1}{20.0cm}-\frac{1}{60.0cm}}=30.0cm$
$d_{od}=-5cm$
$d_{id}=\frac{1}{\frac{1}{f}-\frac{1}{d_{od}}}=\frac{1}{\frac{1}{-10.0cm}-\frac{1}{-5cm}}=10.0cm$
$m=m_1\times m_2=\frac{d_{ic}}{d_{oc}}\times\frac{d_{id}}{d_{od}}=\frac{30.0cm}{60.0cm}\times\frac{10.0cm}{-5.0cm}=-1$
