In February 2010 Shell and Cosan formed a 50:50 joint-venture, Raízen, comprising all of Cosan's Brazilian ethanol, energy generation, fuel distribution and sugar activities, and all of Shell's Brazilian retail fuel and aviation distribution businesses. In March 2010, Shell announced the sale of some of its assets, including its liquid petroleum gas (LPG) business, to meet the cost of a planned $28bn capital spending programme. Shell invited buyers to submit indicative bids, due by 22 March, with a plan to raise $2–3bn from the sale. In June 2010, Royal Dutch Shell agreed to acquire all the business of East Resources for a cash consideration of $4.7 billion. The transaction included East Resources' tight gas fields.
Try to answer this question if possible (otherwise reply "unanswerable"): Royal Dutch Shell agreed to acquire all the business of what entity in June 2010?
East Resources