Step 1: Start with the initial depth of the submarine, which is -650 feet below sea level.
Step 2: Ascend 255 feet. Since ascending means going up, we add 255 to the initial depth.
-650 + 255 = -395
Now the submarine is at a depth of -395 feet below sea level.
Step 3: Dive 50 feet. Since diving means going down, we subtract 50 from the current depth.
-395 - 50 = -445
Thus, the new position of the submarine is -445 feet below sea level.