In nature, oxygen has three common isotopes. The atomic masses and relative abundances of these isotopes are given in the table below.

Isotope Atomic Mass (amu) Relative Abundance
O-16          15.995                          99.759%
O-17          16.995                             0.037%
O-18          17.999                               0.204%
Calculate the average atomic mass of oxygen. Show all of your calculations below.