9. On the fictional planet Andoria, a somewhat fictional element has two naturally occuring isotopes, with atomic masses of 84.9141 and 86.9426 a.m.u... Percent abundance of the first isotope is 75.05%. What is the atomic mass of the element? A) 84.97 a.m.u. B) 85.42 a.m.u. C) 85.75 a.m.u. D) 86.24 a.m.u. E) 86.67 a.m.u