Two Clear but Non-Mixing Liquids Each of Depth 15 Cm

Multiple Choice

Two clear but non-mixing liquids each of depth 15 cm are placed together in a glass container.The liquids have refractive indices of 1.75 and 1.33.What is the apparent depth of the combination when viewed from above?

A) 19.8 cm
B) 23.1 cm
C) 17.7 cm
D) 9.9 cm
E) None of these is correct.