A design was constructed by using two rectangles, ABCD and A'B'C'D'. RectangleA'B'C'D' is the result of a translation of rectangle ABCD. The table of translations isshown below. Find the coordinates of point B.

From the table, to transform points in rectangle ABCD into A'B'C'D', we have to apply the next rule: (x, y) → (x+1, y-3). That is,
A(2, 4) → (2+1, 4-3) → A'(3, 1)
C(2, -1) → (2+1, -1-3) → C'(3, -4)
D(-6, -1) → (-6+1, -1-3) → D'(-5, -4)
Then, if we want to transform a point in A'B'C'D', the rule is: (x,y) → (x-1, y+3). Applying this rule to point B', we get:
B'(-5, 1) → (-5-1, 1+3) → B(-6, 4)