[CLOSED] Vector3.InverseTransformPoint() workaround?

Please can someone point me to solving this?
Is there some workaround for method Transform.InverseTransformPoint(Vector3) where I wnat to supply Vector3 instead of Transform?

//this is what I'm after
Vector3.InverseTransformPoint(Vector3);

Anyone?

Placed question is irelevant cause I wanted input on function to be Vector3 and does not realized that I already have 2 vectors known so I can compute using simple vector math.