Chemistry mass spectrum question

I'd like some help with this question:

"The element bromine has two isotopes, Bromine-79 and Bromine-81. How many peaks corresponding to Br₂ + ions would be seen in the mass spectrum of bromine? Justify your answer. (2)"

I have found the answer, but I just don't understand it:

becasue Bromine is a group 7 halogen, it's found as Br2, similar to chlorine Cl2, and Iodine, I2.

Hence, in the mass spectrometer because either atom could be either isotope, for Br2 there are 3 combinations of atoms, 79-79, 79-81, or 81-81.

Furthermore, the + is because the molecule is ionised in the mass spectrometer.

It doesn't matter about 79-81 vs 81-79 because it's the same molecule but flipped.

Hope this helps, feel free to ask for more explanation if required

I'd like some help with this question:

"The element bromine has two isotopes, Bromine-79 and Bromine-81. How many peaks corresponding to Br₂ + ions would be seen in the mass spectrum of bromine? Justify your answer. (2)"

I have found the answer, but I just don't understand it: