The answer is; "Quadrilateral ABCD is congruent to quadrilateral A′B′C′D′ because you can map quadrilateral ABCD to quadrilateral A′B′C′D′ using a translation 7 units to the right, which is a rigid motion."
If all three radical expressions can be simplified to have a radicand of 3xy, than each original expression has a radicand that is a product of 3xy and a perfect square.