Final answer:
The total combined number of negatively charged particles in oxygen and neon is 18.
Step-by-step explanation:
Oxygen (O) has an atomic number of 8, meaning that a neutral atom has 8 electrons. Neon (Ne) has an atomic number of 10, meaning that a neutral atom also has 10 electrons. The total combined number of negatively charged particles in oxygen and neon, therefore, is 8 + 10 = 18.