Firm A is considering a merger/acquisition with Firm B. Based on the following data, what is the stock exchange ratio if Firm A negotiates a merger with Firm B and if all the synergy gain goes to Firm A's shareholders?

Firm A:

Market value of debt: $4 million

Market value of equity: $6 million

Number of shares: 0.5 million

Estimated total firm value based on value-based management model if the merger takes place: 12 million

Firm B:

Market value of debt: $6 million

Market value of equity: $7 million

Number of shares: 0.5 million

Estimated total firm value based on value-based management model if the merger takes place: 15 million