Walgreen Co. has agreed to pay $6.7 billion in cash and stock to buy a 45 percent stake in European health and beauty retailer Alliance Boots. The company has an option to buy the rest of the company in about three years, according to reports. Under the deal, Walgreens gains access to stable European markets as well as emerging markets like China. The company recently reported its fiscal third-quarter earnings dropped 11 percent to $537 million, or 62 cents per share, as revenue decreased three percent to $17.75 billion.