A collector of rare items is negotiating with a museum. He wants to sell a spear he claims to have been used to kill a mammoth over 11,000 years ago. A spear that size would have started with around 4g of
Carbon-14, and the museum tests show it now contains around 2g. How many half-lives have passed since the spear was carved?

I'm not sure if you maybe forgot to add in some information but I can give you the equation you will need to solve this..! (just without the bit of infomration you might need)

In this case you'll be solving for t and I can help you with your first step, you'll divide 2 by 4, getting you to:

igneous rocks also form where plates converge. the subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. metamorphic rocks are formed mainly in the lithosphere, wherever there is high pressure and high temperature. -woods

there are no atoms