Firm C has a market value of $600 million and 30 million shares outstanding. Firm D has a market value of $200 million and 20 million shares outstanding. Now firm D is contemplating acquiring firm C. Firm Ds financial controller concludes that the combined firm with synergy will be worth $1 billion and firm C could be acquired at a premium of $100 million. To make the value of stock offer equivalent to cash offer of $700 million to firm C, what would be the proper exchange ratio of the stocks of the two firms?