Answer:
The Answer is B: subtract atomic mass from atomic number. I remember doing this in 8th grade!!!:)
Step-by-step explanation:
The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom and the atomic number.