A persоn hаs а fаr pоint оf 200 cm. The distance from the cornea-lens to the retina is 1.8 cm. Suppose the eye’s power of accommodation is 3 diopters. What is the refractive power of eyeglasses should be used so the person can see objects as close as 20 cm clearly? Ignore the gap between the eyeglasses and eyes.