A student is reading a lecture written on a blackboard. The lenses in her eyes have a refractive power of 68.80 diopters, and the lens-to-retina distance is 1.461 centimeter.
(a) Determine how far is the blackboard from her eyes?
(b) If the writing on the blackboard is 5.90 centimeter high, find the size of the image on her retina?