Why is negative and positive numbers opposite?

Negative and positive numbers are considered opposites because they represent values that are equidistant from zero on the number line, but in opposite directions. For example, +5 and -5 are both five units away from zero, but one is in the positive direction and the other in the negative direction. This relationship highlights the concept of balance and symmetry in mathematics, where adding a positive number and its corresponding negative number yields zero.