* Understanding the Notation: Br-80 tells us we're dealing with an isotope of bromine. The "80" represents the mass number, which is the total number of protons and neutrons in the nucleus.

* Atomic Number: Bromine (Br) has an atomic number of 35. This means a neutral bromine atom has 35 protons and 35 electrons.

* Charge: The " -" indicates that this bromine atom has gained an extra electron.

Calculation:

* Start with the number of electrons in a neutral bromine atom: 35

* Add one electron due to the negative charge: 35 + 1 = 36

Therefore, Br-80 has 36 electrons.