# How to set v in ReflectionTransform[v,p]?

GROUPS:
 Reflect Green Line about Blue Reflection Line, GreenPoint P is center of reflection. GreenPoint P's coordinate is known. After use ReflectionTransform[v,GreenPoint] I want to get this image. How to set v in ReflectionTransform[v,p]? Blue line L's equation is y = -Sqrt[3]x + 15 line L's slope is -Sqrt[3].