A 50-year-old man uses +2.5-diopter lenses to read a newspaper 25 cm away. Ten years later, he

Question:

A 50-year-old man uses +2.5-diopter lenses to read a newspaper 25 cm away. Ten years later, he must hold the paper 35 cm away to see clearly with the same lenses. What power lenses does he need now in order to hold a paper 25 cm away? (Distances are measured from the lens.)