Answer:
The ratio of the area of ABCD to the area of EFGH is 9:1.
Explanation:
Let us assume that the shapes are rectangles and they are similar. If the two shapes are similar then their sides are in the same proportion. Therefore the ratio of the sides are in the same proportion.

The area of ABCD = AB × BC = 18 × 24 = 432
The area of EFGH = EF × FG = 6 × 8 = 48
The ratio of the area of ABCD to the area of EFGH = Area of ABCD / Area of EFGH = 432 / 48 = 9/1 = 9 : 1