Marseille Manufacturing (MM) is considering an IPO. MM currently has 13 million shares outstanding and I currently own 8 million of those shares. MM plans to sell 3 million shares in the IPO. If all...

Marseille Manufacturing (MM) is considering an IPO.  MM currently has 13 million shares outstanding and I currently own 8 million of those shares.  MM plans to sell 3 million shares in the IPO.  If all the new shares are primary shares, then what will my new ownership percentage be?  If I decide to replace some of the primary shares with some of my shares as secondary shares in the IPO, then how many of my shares can I sell and still maintain 50% ownership?