algebra 1
posted by josh .
The midpoint of XY is point M(12,5). If the coordinates of X are (3,3), what are the coordinates of Y?

let the other endpoint be Y(a,b)
(a+3)/2 = 12 and (b3)/2 = 5
a+3 = 24 and b  3 = 10
a = 27 and b = 13
Y is (27,13)