The element loncapium has three isotopes. The first, Lc-79 has a mass of 78.8226 amu and makes up 15.11% of a standard sample. The second isotope, Lc-81, has a mass of 80.5371 amu and makes up 39% of a standard sample. The third isotope, Lc-82, has a mass of 81.9134 amu and makes up the remainder of a standard sample. What is the average atomic mass of this element?