The relative atomic mass of an atom can be found by comparing the mass of that atom to the mass of a carbon-12 atom.

Here's a breakdown:

* Carbon-12: The carbon-12 atom is the standard reference for atomic mass. It has been assigned a mass of exactly 12 atomic mass units (amu).

* Relative Atomic Mass: This is the ratio of the average mass of an atom of an element to 1/12th the mass of a carbon-12 atom. It's a unitless value that reflects how much heavier or lighter an atom is compared to carbon-12.

For example:

If an atom of oxygen is found to be 1.333 times heavier than a carbon-12 atom, its relative atomic mass would be 16 amu (1.333 x 12 amu).