your answer would be
6 ways for 1st place
5 ways for 2nd place
4 ways for 3rd place
3 ways for fourth place
and in total there are 360 ways in total.
(6*5*4*3=360)
On a phone here and no access to paper but you must first find the midpoint of AC which is the average of the coordinates. The perpendicular bisector will have a gradient that multiplies by AC's gradient to make -1. This will obviously pass through its mid point so as long as you know how to use y=mx+c you should be good.
