Without Glasses,a Person Can Comfortably Read a Magazine When It

Multiple Choice

Without glasses,a person can comfortably read a magazine when it is held at 60 cm from his eyes.What should be the focal length of his contact lenses to allow him to read the magazine comfortably at a distance of 30 cm?

A) -30 cm
B) +30 cm
C) -60 cm
D) +60 cm
E) +90 cm