If you subtract the atomic number from the weight, what is the interpretation of the answer? (e. g. 14-7=7; think of a subatomic particle).

If we subtract the atomic number from the weight, we get the number of neutrons in the particle. This is because protons and neutrons each have a weight of 1, while electrons are 0. And since the atomic number is also the number of protons in the atom, subtracting it from total weight gives us the number iif neutrons.

What’s the question here ?

What is it that you need with?