Cost of capital problem

Friends pls solve ma query.. While calculating WACC if retained earnings are given in book value but not in market value....i have seen 2 things in same type of 2 questions. 1. They had bifercated market value of ESC in the ratio of book value of Esc nd retained earnings. 2. . In t other numerical they hadnt take retained earning at all. ..pls tel me t corect procedure regaring this