A myopia person can see things clearly only when they lie between 10 cm and 80 cm from the eye. Which lens would enable him to see the moon clearly ?

Explanation

Given, far point x = 80 cm.
To see the moon clearly, he has to use spectacles with concave lens of focal length, f = -x = -80 cm
Power, `= -1.25 D P = (80)/(f)`