The midpoint of xy is (3,-5) the coordinates of point x are (1,5) what are the coordinates of point y?

the answer is y: (5,-15)

the x goes up by 2, so we do another jump of 2 to reach 5

the x drops by 10 so we do another drop by 10 to get to -15

We have

[1 + x]/2 = 3                 and                               [ 5 + y] / 2  = -5

                   Multiply both sides of each equation by 2   

1 + x  = 6                                                           5 + y = -10

subtract 1 from each side                                   subtract 5 from both sides

x = 5                                                               y = -15

So....the other point is  (5, -15)