What is the focal length and power of the reading galsses required by a person whose near point is 90 cm?

The near point of a person suffering from hypermetropia is 75 cm. calculate the focal length and power of the lens required to enable him to read the newspaper which is kept at 25 cm form the eye.

Write expression for the focal length and power of a lens combination.

An iluminated object and a screen are placed 90 cm apart.Determine the focal length and nature of the lens required to produce a clear image on the screen,twice the size of the object.

If the focal length of a converging lens is 50 cm. What is the power of the Lens ?