Boris is an unmarried systems specialist with a public accounting firm.During all of 2017, he is on temporary assignment in London.He pays $21,000 in British income tax on his $100,000 salary.Boris knows little about taxes and seeks your advice on the taxability of the salary he earns while in London.Write Boris a memorandum explaining the tax treatment of his London salary.Assume that Boris has no other income sources and that he does not itemize deductions.