Li, the general manager of a courier business, is on holiday in Bali. He ran out of money. He telephones Ahmed, the most knowledgeable, experienced and trusted courier. Li asks Ahmed to sell an old coffee machine for at least $500 and deposit the money to Lis bank account. The next day, Li was surprised to find that only $250 was deposited to his account. He telephones Ahmed. Ahmed explains that he sold the coffee machine to his best friend and could not rip him off by charging $500. Li is furious. Advise Ahmed if he is liable for the balance of the money and if so on what grounds? Your answer must refer to relevant agency case law.