Question

Refer to the attached picture. ​

Answer 1

The first refracting surface ABC forms the image I, of the object O, The image I, act :as a virtual object for the second refracting surface ADC, which forms the real image I as shown in the diagram. 

For refraction at ABC,

For refraction at ADC,

Answer 2

The first refracting surface ABC forms the image I, of the object O, The image I, act :as a virtual object for the second refracting surface ADC, which forms the real image I as shown in the diagram.