To calculate the number of years that make up 5 half-lives for carbon-14 (^14C), you multiply the length of one half-life by the number of half-lives:
1 half-life of ^14C = 5,730 years
So for 5 half-lives:
5 half-lives = 5 × 5,730 years = 28,650 years
Thus, the answer is:
28,650 years