Radioactive decay can be described by the following equation In A = In Ao - kt where Ao is the original amount of the substance, A is the amount of the substance remaining after time t, and k is a constant that is characteristic of the substance. -1 For the radioactive isotope lead-210, k is 3.30 x 10-2 years If the original amount of lead-210 in a sample is 51.6 mg, how much lead-210 remains after 19.8 years have passed? mg