Meet "Casey Runner". Casey can run backwards or forwards, and can also face left (the negative direction) or right (positive).
Knowing that ++ or −− make a positive, and +− or −+ make a negative (read How to Add and Subtract Positive and Negative Numbers) see if you can help Casey reach the finish line.
Try This In Real Life!
Mark a number line on the ground (using tape or chalk) just like above.
Then throw a die to decide distance, like this (you can put stickers on the die to make it easier):
See who wins!