Question

Rectangle A′B′C′D′ is the image of rectangle ABCD after a dilation.

Answer 1

The dimensions of the original figure is a 4 x 3 rectangle, and the dilated figure's dimensions are 12 x 9.  
The length of 12 is 3 times more than the length of 4, and the width of 9 is 3 times more than the width of 3. 
This means that the scale factor of the dilation is 3. Hope this helps!