If you are given the mass number and atomic number of an atom explain how you would find the number of protons neutrons and electrons

Atomic number is same number as the protons ...

Neutrons = Mass number - Atomic number (protons)

Electrons are same number as protons unless the element has a charge ...

If it has a charge of + 2 it means that the element has 2 less electrons than the neutral atom. If it has a charge of - 2 it means that the element has 2 more electrons than what it is supposed to ...