Answer: There are many ways. (Check Explanation)
Explanation: Electrons are found outside of the nucleus. Now in the middle of the nucleus there are protons in neutrons. The way to determine the number of neutrons in the Bohr Model are many ways.
Number one, if the neutrons, protons, and electrons were color coded, take away the electrons and you are left with the 2. Then find out which color corresponds to the neutron.
If it isn't color coded, then the protons and electrons should usually be marked with either + or - on it. The one without any of this and that is in the nucleus is the neutron. Last but not least, on some of the models, it can show many protons or neutrons are in the nucleus. For example the potassium bohr model. (Check image) On here, 19+ means 19 protons and 20N means 20 neutrons.