Question

convex lens front surface facing the object classify distant object and distance between lens center and screen

Answer 1

The virtual image of the convex lenses is taking with the focal distance of proper images.

This is managed with the front focal length of a lens and able to deliver thickness and curvature of the lens surfaces manages together to define actual points.

This is what it is managed with any point on the object taken back with focal distance of a convex lens.

Answer 2

distance between. lens center and screen of distant object of window is - 20.1