I like to call it the oppsite of the Number on the cordinate grid say you have (1,-1) well its oppsite is (-1,-1)
or say we have (6,5) well its oppsite or as hectictar had explained how she calls it reflected is (-6,5)
Also to count on a graph you just count each corrdinate across. See because I counted it the to points are 6 corrdinates apart..... Oh yeah thanks hectictar for your image I saved it and did that on it hope your not mad or anything XD
~Nickolas