Sadflatte's Corporation's stockholder's equity at December 31, 2016 included the following:
8% Preferred stock, $10 par value $2,000,000
Common Stock, no par $20,000,000
Additional paid-in capital $8,000,000
Retained Earnings $8,000,000
Prologa Corporation purchased a 30% interest in Sadflatte's common stock from other shareholders on January 1, 2017 for $11,600,000. What was the book value of Prologa's investment in Sadflatte?