CONFIDENTIAL DRAFT FOR PURPOSES OF SETTLEMENT DISCUSSIONS ONLY September 3, 2013 bgC3 LLC Attention: William H. Gates, Manager Dear Bill: RE: Letter of Agreement Regarding Purchase of Interest in Investment Entity This letter sets forth the agreement by and between bgC3 LLC ("bgC3"), and me, Dr. Boris Nikolic ("Dr. Nikolic"), with respect to the purchase by bgC3 from Dr. Nikolic of Dr. Nikotic's interest created under our prior agreement in a certain $30 Million to $50 Million Investment Entity (the "Investment Entity"). With respect to bgC3's purchase from Dr. Nikolic of Dr. Nikolic's interest in the Investment Entity, bgC3 and Dr. Nikolic have agreed as follows: Termination of On February 15, 2014, Dr. Nikotic's employment with bgC3 shall Employment and terminate, as will all financial and business relationships between Dr. Business and Nikolic, on the one hand, and each of bgC3, William H. Gates, Melinda F. Financial Gates, the Bill and Melinda Gates Foundation and all other entities owned Relationships or controlled by William H. Gates, on the other hand, except for those relationships created by the provisions of this Agreement. Sale and Purchase Dr. Nikolic shall sell, transfer and convey to bgC3, and bgC3 shall of Interest in purchase from Dr. Nikolic, all of Dr. Nikolic's right, title and interest in Investment Entity and to the Investment Entity for a purchase price equal to the aggregate of all amounts payable under all Investment Entity Payment Demands (as hereinafter defined) to be made by Dr. Nikolic to bgC3 during the Payment Period (as hereinafter defined) pursuant to this Agreement. Such sale and purchase shall be deemed to have been completed, effective upon bgC3's payment in full to Dr. Nikolic of all amounts payable under all Investment Entity Payment Demands to be made under this Agreement, together with all other amounts due and payable by bgC3 to Dr. Nikolic under this Agreement. Advance SE-251912 vl bgC