If your kid is sharp. he or she is going to want to know where the Egyptians found horses with which to chase the fleeing Israelite: Didn't they all die during, the animal plague(9:6)... and again during hail (9:19)?
The first place to look, of course, is the Documentary Sources -- and that's something of a help: Pharaoh's pursuing chariots are mentioned in both P and E, while the plagues that say all the animals died are both J.
However, as noted, two plagues are reported to have killed all the animals, and both are J.
So a better answer comes from Abarbanel, and slightly worse answer is given by Ramban
All doesn't really mean all. It means some, ie, its an exaggeration
The Israelites sold the Egyptians replacement horses and livestock.
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