∆abc is mapped to ∆a'b'c' using each of the given rules. select each of the rules which would result in the two triangles being congruent.

(x, y)→(x+3,y−4)

(x, y)→(3x,3y)

(x, y)→(0.4x,0.4y)

(x, y)→(−x,−y)

The first one is two translations. The last one is two reflections. Those two don't change the size of the sides or angles, so the triangles before and after are congruent. The second and third rules change the lengths of the sides, so those don't qualify.

39 is the answer