how long in calculus

Question

A wooden artifact from an ancient tomb contains 30 percent of the carbon-14 that is present in living trees. How long ago, to the nearest year, was the artifact made? (The half-life of carbon-14 is 5730 years.)

Answer 1

This is not only a Calculus question, it's also a traditional question in Algebra II, encountered when Exponential decay is discussed.  Does it now ring a bell>