Income is conventionally denoted by "Y" in economics. John Hicks applied "I" for income, but Keynes wrote to him in 1937, "immediately after trying both of those, I believe it is actually simpler to use Y for income And that i for expense. Illustrations are immediately compiled from on line https://fummel-income-streams40858.blogsumer.com/34424717/the-ultimate-guide-to-fummel-income-streams