Working Out Abraham's Years From the Covenant to Haran

Our father Abraham was seventy years old at the time when the Holy One, blessed be He, spoke with him at the Covenant Between the Pieces, as it is said, "And it came to pass at the end of four hundred and thirty years" (Exodus 12:41) [counting from the covenant to the Exodus]. Then he returned to Haran and remained there five years. For thus it says, "And Abram was seventy-five years old when he departed from Haran" (Genesis 12:4). It turns out that from the Dispersion [of the generation of the Tower] until Abraham our father departed from Haran was twenty-six years. These are the twelve years that they served Chedorlaomer, and in the fourteenth year Chedorlaomer came [against them] (compare Genesis 14:4-5). That same year in which Abraham departed from Haran was the year of the famine, and he went down to Egypt and spent three months there, and came and settled in Hebron. That is the year in which he defeated the kings.