If you know how much radioactive material the organism had to begin with, explain how you could use half-life to determine its age now.

We can calculate it with the radioactive half life equation

Explanation:

If we already know the initial amount of radioactive material and its half life, we can leave that material for a specific known time and then measure how much of the material is left (since it follows the radioactive deacay) and use the results in the following formula:

Where:

is the final amount of the material

is the initial amount of the material

is the time elapsed

is the half life of the radioactive compound