"Point reflection" or "point symmetry" is a basic concept in geometry where a given point, P, at a given position relative to a mid-point, Q has a corresponding point, P1, which is the same distance from Q but in the opposite direction.
Given two points P and Q, output the symmetric point of point P about Q. Each argument is a two-element array of integers representing the point's X and Y coordinates. Output should be in the same format, giving the X and Y coordinates of point P1. You do not have to validate the input.
This kata was inspired by the Hackerrank challenge Find Point
def symmetric_point(p, q)
[ 2 * q.first - p.first, 2 * q.last - p.last ]
end