Atired physics professor can easily read the fine print of the financial page when the newspaper is held at arm's length, 61.5 cm from the eye. what should be the focal length of an eyeglass lens that will allow him to read at the more comfortable distance of 26.0 cm?

45.04 cm

Explanation:

The tired physics professor red easily at a distance of 26 cm

So v = 26 cm

And it is given that object distance that is u = 61.5 cm

There is relation between focal length object distance and image distance that is

Here f =focal distance v = image distance and u = object distance

So

So f=45.04 cm

because if the tool that you are using is not balanced it there would be false mass.