If this is graphing you have to graph it first to find the area.
Nah homie it's always gonna be the inside of a triangle. hope this helps, have an amazing day :)
The answer to your questions is B. {(4, 2), (4, –2), (9, 3), (9, –3)} because you don't have a repeat of a number the X side which is your output. I hope that this is the answer that you were looking for and it has helped you.
All possibilities = 9!
possibilities that harry sits at an end = 8! + 8!
possibilities that harry doesn't sit at an end = 9! - 8! -8!