Answer: B' is (3, -3)
Explanation:
When we have a point with coordinate (x, y) and we do a dilation (around the center) with a scale factor of A, the coordinate of the new point will be:
A*(x,y) =(A*x, A*y)
Here our point is (1, -1) and the factor is 3, so the new point will be:
(3*1, 3*-1) = (3, -3)