Question

Why two negative integers must be added? Why one positive and one negative integer must be subtracted? I want appropriate reason. Not the process or explanation.​

Answer 1

Answer:

Each number has an "additive inverse" associated to it (a sort of "opposite" number), which when added to the original number gives zero. ... The fact that the product of two negatives is a positive is therefore related to the fact that the inverse of the inverse of a positive number is that positive number back again.