The question is referred to a particular pair of triangles.
They are two "siamese" right triangles. The side that they share is the hypotenuse of both triangles.
The other sides that are marked as congruent are the heights of each triangle.
Then, you can use the Hypotenuse Leg theorem to prove the congruence of both triangles.
The hypotenuse leg theorem states that any two rigth triangles that have congruent hypotenuse and a corresponding, congruent leg are congruent triangles.
