The midpoint of \overline{\text{AB}} AB is M(-1, 7)M(−1,7). If the coordinates of AA are (4, 8)(4,8), what are the coordinates of BB?

Answer 1

If the co-ordinates of the endpoints of a line are (a,b) and (c,d), the co-ordinates of the midpoint are [(a+c)/2,((b+d)/2]. From this hint you should be able to solve the ;problem.