Abraham born 2000BC Issac born 1901BC IJacob born 60 years later at
1840BC.  As an old man, left for Egypt maybe 80 years later, era
1760BC... Exodus was 1440BC (1Kings6) or the Jews were 220 years in
Egypt.
You get the 400 years in Egypt beginning at Jacob's birth, as he was
the father of the 12 tribes.
Lewis