Chapter 25 - Vision and Optical Instruments - Learning Path Questions and Exercises - Exercises - Page 871: 14

Power of top half of the lens is $-0.2D$ and that of the lower half is $+2.57D$

The doctor recommended bifocal lenses. For upper half :- $P_{upper}=\frac{1}{f}=\frac{1}{do}+\frac{1}{di}=\frac{1}{infinity}+\frac{1}{-5}=-0.2D$ For lower half :- $P_{lower}=\frac{1}{f}=\frac{1}{do}+\frac{1}{di}=\frac{1}{0.25}+\frac{1}{-0.7}=+2.57D$