According to Exhibit $32\mathrm{.}9,$ debt adds value to California Pizza Kitchen. How does debt add value to California Pizza Kitchen? Which MM theory Case is consistent with this pattern?

According to Exhibit $32\mathrm{.}9,$ when a firm increases its debt level to $10\%,20\%,$ and $30\%$ and uses the capital raised from debt to repurchase stocks, the market value of equity drops by less than $10\%,20\%,$ and $30\%.$ For example, at a $10\%$ debt level, the equity level becomes $97\mathrm{.}63\%(628,516/643,773)$ of that in the current plan. What causes the discrepancies? Who would reap the added value created by financial leverage change? Stockholders or debt holders?

Please use Exhibit $32\mathrm{.}9$ and calculate the ROE $($Return on Equity$)$ and Beta for different debt ratios. According to MM theory Case $2,$ how will the firm$$s business risk, financial risk, beta, cost of equity, ROE, and WACC change with debt level?