'Years' in the Bible

Then three years later I did go up to Jerusalem to get acquainted with Cephas (Peter), and I stayed with him fifteen days.

Then after a period of fourteen years I again went up to Jerusalem, [this time] with Barnabas, taking Titus along also.

This is what I mean: the Law, which came into existence four hundred and thirty years later [after the covenant concerning the coming Messiah], does not and cannot invalidate the covenant previously established by God, so as to abolish the promise.

[For example,] you observe [particular] days and months and seasons and years.