how to calculate ROE after repurchase.Should we use market values vs. Book values ?

Data:

Loan $950.00 million Revenues $2,824.40 million Used to purchase Reiman $726.30 million Operating Profit $263.10 million Used to repurchase shares $223.70 million Net Income $110.90 million A Shares $20.85 per share Total Assets $2,829.00 million B Shares $27.78 per share Sell for A Shares

Book Value Equity $436.30 million Interest Rate 6% # of Outstanding shares before purchase $102.70 million Conversion Rate from B to A 1.24 Divident per share $0.20 Tax Rate 30% Repayment Plan Year 1 $132 million Year 2 $32 million Year 3 $57 million Year 4 $82 million Year 5 $82 million Year 6 $565 million Discount Rate 10%