3 times the length of the corresponding sides of the original rectangle.
Step-by-step explanation:
Because the length measures have not been given for the original rectangle, the exact measures of A'B'C'D' can not be found. But, because the factor is 3, then the side lengths have been tripled. For example, side A'B' would be 3 times the length of side AB. Side C'D' would be 3 times the length of side CD.
