Chemistry

Carbon has two naturally occurring isotopes: C-12 with a natural abundance of 98.89% and isotopic mass of 12 amu, and...","Carbon has two naturally occurring isotopes: C-12 with a natural abundance of 98.89% and isotopic mass of 12 amu, and C-13 with a natural abundance of 1.11% and an isotopic mass of 13.0034 amu. What is the atomic mass of carbon?