The​ half-life of a certain element is about 5900 years. Use the radiometric dating formula to complete parts​ a) and​ b) below.
a. A piece of cloth is painted with organic dyes. By analyzing the dye in the​ cloth, it is found that only ​68% of the certain element in the dye remains. When was the cloth​ painted?
b. A​ well-preserved piece of wood found at an archaeological site has 12.8​% of the certain element that it must have had when it was alive. Estimate when the wood was cut.