How many times heavier is one atom of carbon than one atom of oxygen?

Mass of 6.022 X 10²³ atoms of carbon = 12 g
Mass of 1 atom of carbon, M_C = (12 / (6.022 X 10²³)) g……(1)
Mass of 6.022 X 10²³ atoms of Oxygen = 16 g
Mass of 1 atom of oxygen,M_O = (16 / (6.022 X 10²³)) g…….(2)
Divide (1) by (2)
M_C / M_O = 12 / 16
M_C / M_O = 0.75
M_C = 0.75 M_O
Mass of one carbon atom is 0.75 times that of Oxygen atom.