Let's say you wanted to add 2 and 3 together. The answer is 5. You can start at 2 on the number line, then move 3 spots to the right until you hit 5
OR
you can start at 3 on the number line, then move 2 spots to the right to land on 5.
Either way you get the same result. The first number tells you where to start, and the second number tells you how many spots you move to the right.
note: if the second number is negative, then you move to the left that many units.
