Answer:
The amount between each. Since you didn't attachment any further information like the amount of M, N, and P or a graph chart- I'll only be able to give an example.
Let's say M is equal to 3, N is equal to 1, and P is equal to 2. All together these spaces add up to 6 which can be evenly space out or distributed unevenly.
Like M:N= 3:1 or N:P = 1:2. As you can tell all together (all you have to do is add 3&1 or 1&2) you'll get the result of 4 or 3 and they aren't similar. Let me know if this helps! I know sometimes seeing technically terms and numbers can be difficult so I tried to explain with words as best I could. Good luck to you.