>Well I think the explanation is two fold. First that Adam and Eve were perfect, therefore they lived much longer. You have other historical biblical figures living for well over 150 years, it stands to reason that Adam and Eve likely lived longer, it never says how old they are or when they die or even when they had children.

>Second of all it doesn't say Adam and Even had only two children, only that Cain and Abel were two of their children. It could be Eve was popping them out every 9 months or something, it doesn't say she wasn't so maybe they had a couple hundred kids, some went to live in the land of Nod.

Genesis 5:3-5 says Adam was 130 when Eve gave birth to Seth who was born after Cain killed Abel, then lived for another 800 years fathering more children. It doesn’t say how long between their creation and when they were kicked out of the garden, but it’s reasonable to assume there was enough time between their exile and when Abel was killed they had time to knock boots a few times.