If "a" is a positive number:

* A negative number plus a positive number can result in a negative, positive, or zero result depending on the specific numbers.

* Example: -5 + 3 = -2 (negative)

* Example: -2 + 5 = 3 (positive)

* Example: -4 + 4 = 0 (zero)

If "a" is a negative number:

* A negative number plus another negative number always results in a negative number.

* Example: -5 + (-3) = -8

If "a" is zero:

* A negative number plus zero always results in the negative number itself.

* Example: -5 + 0 = -5

Let me know if you have a specific example in mind, and I can help you calculate the result!