A double-concave lens has equal radii of curvature of 15.1 cm. An object placed 14.2cm from the lens forms a virtual image 5.29cm from the lens. What is the index of refraction of the lens material?
a) 1.77
b) 1.98
c) 1.82
d) 1.90 <--- Correct answer, but I do not know how to solve for it.
e) 1.04