An artifact contains 1/4 as much carbon-14 as the atmosphere. How old is the artifact

The artifact appears to have gone through 2 half-lives.

One half-life for Carbon-14 is 5730 years.

After 5730 years, there would be 1/2 as much carbon-14

After another 5730 years, there would be 1/4 as much carbon-14

The answer is roughly 11,460 years