Write an equation to solve:
1. A scuba diver dives down 20 feet in the ocean. He then swims 11 feet back up towards the surface. What is the position of the scuba diver relative to the surface?
2. You and your friend play a video game. You have a final score of 40 points, and your friend has a final score of -21 points. By how many points did you win?
