Did the Hebrews spend time in Egypt for 400 or 430 years?

I know this seems like an old question but here’s the contradiction I’m struggling with:

400 years

“Then the LORD said to Abram, “Know for certain that your descendants
will be strangers in a land that is not their own; they will be
enslaved and mistreated four hundred years.”- Genesis 15:13

“And God spoke to this effect—that his offspring would be sojourners in a land belonging to others, who would enslave them and afflict them 400 years.”- Acts 7:6

“In the fourth generation your descendants will return here, for the
iniquity of the Amorites is not yet complete.”- Genesis 15:16

*As a side note, could anyone explain how fourth generation links to 400 years? Thanks.

430 years

“What I mean is this: The Law that came 430 years later does not
revoke the covenant previously established by God, so as to cancel the
promise.”- Galatians 3:17

“Now the duration of the Israelites’ stay in Egypt was 430 years.”- Exodus 12:40