Observe the translation for every point.
For Point A
A(2, 4) ⇒ A'(3, 1)
we can observe that the x coordinate is increased by 1 and the y coordinate is decreased by 3
For Point C
C(2, -1) ⇒ C'(3, -4)
Same with point C, the observation is the same as Point A.
So the transformation is (x, y) ⇒ (x + 1, y -3)
For Point B :
B(x, y) ⇒ B'(-5, 1)
x + 1 = -5
x = -5 - 1 = -6
y - 3 = 1
y = 1 + 3 = 4
B will be : B(-6, 4)
For Point D :
D(-6, -1) ⇒ D'(x + 1, y - 3)
-6 + 1 = -5
-1 - 3 = -4
D' will be : D'(-5, -4)