Pre-cal matrix equation?

i don't like asking test questions on here but i don't know the answer and this is my third attempt at this. it wasn't covered in the course and nobody i know can with it. i don't need the answer, just an explanation on how to solve it. step by step if you have the time !

Which point on the scatter plot is an outlier? a scatter plot is show. point m is located at 3 and 3, point p is located at 5 and 5, point n is located at 5 and 7, point l is located at 6 and 2. additional points are located at 1 and 3, 2 and 3, 2 and 4, 3 and 4, 3 and 5, 4 and 5, 4 and 6, 5 and 6. point p point n point m point l