Answer
(a) $6.0$
(b) $35.0cm$
Work Step by Step
(a) The greates magnification can be determined as
$M_{total}=\frac{f_{objective}}{f_{eyepiece}}=\frac{f_{max}}{f_{min}}$
We plug in the known values to obtain:
$M_{total}=\frac{30.0}{5.0}=6.0$
(b) We know that
$L=f_{objective}+f_{eyepiece}$
We plug in the known values to obtain:
$L=30.0+5.0=35.0cm$