How long were the Israelites enslaved in Egypt?

Question:

How do you explain GENSIS 15:13, the LORD told Abraham that the chosen people would be enslaved for 400 years yet in EXODUS 12:40, we are told that the children of Israel were in Egypt for 430 years?

In the first case, the Genesis 15 text, God was speaking to Abraham using the approximate time, like we generally do today. For example, today we say that Jesus was born some “2,000 years ago” yet we also say that He was crucified some “2,000 years ago”. We are speaking generally in both cases although; there is a period of 33 years from the time of His birth to the time of His crucifixion. God uses general language in this case because the amount of time was not the key, the slavery itself was what was important for us to know about. In Exodus 12:40, we have an historical record of a past event which gives the exact amount of time.