In a simple microscope,if the final image is formed at infinity,what will be its magnifying power?

In a compound microscope,if the objective produces an image $I_o$ and the eyepiece produces an image $I_e$,then

$A$ compound microscope has an eyepiece of focal length $10 \, cm$ and an objective of focal length $4 \, cm$. Calculate the magnification,if an object is kept at a distance of $5 \, cm$ from the objective so that the final image is formed at the least distance of distinct vision $(20 \, cm)$.

In a Ramsden eyepiece,two planoconvex lenses,each of focal length $f$,are separated by a distance of $12 \ cm$. The equivalent focal length (in $cm$) of the eyepiece is:

$A$ compound microscope has an objective of focal length $1.25 \ cm$ and an eyepiece of focal length $5 \ cm$ separated by a distance of $7.5 \ cm$. The total magnification produced by the microscope when the final image forms at infinity is

In a compound microscope,the magnified virtual image is formed at a distance of $25 \, cm$ from the eye-piece. The focal length of its objective lens is $1 \, cm$. If the magnification is $100$ and the tube length of the microscope is $20 \, cm$,then the focal length of the eye-piece lens (in $cm$) is