Answer:
The earth is about 4.6 billion years old.
Step-by-step explanation:
"The processes of plate tectonics mean that the Earth is constantly recycling its rock, breaking it down into magma in the interior before pumping it back up to the surface once more. ... Based on the very old zircon rock from Australia we know that the Earth is at least 4.374 billion years old."
- the smithsonnian