The result of a adding a positive number and a negative can either be a negative number or a positive number, depending on the sign of the biggest number. If the sign of the larger number is negative, then the result is a negative number. However, if the sign of the larger number is positive, then the result is a positive number.
For example, this addition of +5 and -2 gives the result of 3. However, if one adds together -5 and +2, then the answer is -2. A way to find these answers is to use a number line and follow two simple rules. If one is adding a positive number, then one moves to the right on the line. Conversely, if one is adding a negative number, then one moves to the left on this line.