Im totally lost! a sample from a refuse deposit near the strait of magellan had 60% of the carbon 14 of a contemporary living sample. estimate the age of the sample

In living matter, the proportion of carbon 14, an isotope of normal carbon 12, is constant. When the matter dies, the carbon 14 atoms decay into nitrogen 14 with an emission of radiation such that there will only be half as many carbon 14 atoms every 5570 years. Thus the half-life of carbon 14 is 5570 years. By measuring the emission of radiation, scientists can infer the population of carbon 14 atoms in similar living matter and estimate when it died. (a) In charcoal found in an ancient fire pit on Java, the amount of carbon 14 was found to be 1/16 of that of a living sample of the same size. Estimate the age of the charcoal. (b) A refuse deposit near the Strait of Magellan was excavated in the 1930’s and dated using carbon dating methods. Emissions from carbon 14 disintegrations were found to be occurring 60% of that of a contemporary living sample. Estimate the age of the sample. (c) If ten percent of a radioactive substance decays in 10 years, what is its half-life?