can you help explain how to solve this question?

1. Assume you discovered a relic of biological materials (e.g. papyrus scroll) and you wanted to date it from C14 residues. The specimen contains 1/8 (or 12.5%) of the original C14. How old is the specimen? 1/8 of the original material reflects 3 half-lives of decay. 35730=17,190 years oldI