The things that China Agree to do once the Treaty of Nanjing was signed are: 
 -create a "fair and reasonable" tariff 
 -allow Britain to trade at five ports 
 -surrender the territory of Hong Kon 
 Explanation: 
 Treaty of Nanjing, (August 29, 1842) treaty that closed the first Opium War, the first of the complex treaties among China and outer imperialist powers. China paid the British a compensation, ceded the territory of Hong Kong, and granted to build a “fair and equitable” tariff.