Based on the information given, you can draw the rectangles mentioned in the exercise:
Since they are similar rectangles, their sides are proportional. This means that the ratio of the of the two lengths is equal to the ratio of the two widths. Then, you can set up the following proportion:
Notice that they are similar.
Then, to check the scale factor, you can write the following equation:
Dividing the numerator by the denominator, you get:
Therefore, the answer is: