Well... it only depends what you're working with..
If you're working with both numbers as positive move up (or move right on a number line). But if you're working with both numbers as negatives you would go downward (or move to the left on a number line).. If you have opposite signs for the numbers you would have to subtract the number.
Remember⬇
Positive & Positive = Positive
Negative & Negative = positive (or negative... it depends what you're working with)
Positive & Negative = Negative