the grand isle has 12,000 shares of stock outstanding at a market price of $31.60 per share. the book value per share is $12.08. the firm has earnings per share of $1.86 and a dividend payout ratio of 0.40. what is the firm's sustainable rate of growth? 9.24 percent 10.86 percent 10.57 percent 8.88 percent 9.71 percent