For what values of x and y are the triangles congruent?

a. x=-4. y=-4

b. x=-4, y=4

c. x=4, y=7

d. x=7, y=4

The triangles, or any pair of polygon, are congruent if and only if the corresponding sides have the same lengths and the corresponding angles have the same measures.

From the given choices above, it can be seen that only the choice in A will give us this relationship. Thus, the answer is A. 

The first one is correct