We can use the thin lens equation to find the focal length of the contact lens:
1/f = 1/do + 1/di
where f is the focal length of the contact lens, do is the object distance (the distance from the object to the lens), and di is the image distance (the distance from the lens to the image).
In this problem, the near point of the person is the object, and the image is formed at a distance of 25.0 cm from the eyes (assuming the eyes are not accommodating). Therefore, we have:
do = 125 cm - 25.0 cm = 100 cm
di = -25.0 cm (since the image is virtual)
Plugging these values into the thin lens equation, we get:
1/f = 1/100 cm - 1/-25.0 cm
1/f = 0.01 cm^-1 + 0.04 cm^-1
1/f = 0.05 cm^-1
f = 1/(0.05 cm^-1) = 20 cm
Therefore, the focal length of the contact lens should be 20 cm to allow the person to read a physics book held 25.0 cm from his eyes.