Answer:
9:16
810
Step-by-step explanation:
Let's say the smaller rectangle has length 6 and width 3. Because they are similar with ratio 3:4, the larger rectangle has length 6 * 4/3 and width 3 * 4/3. In other words, length is 8 and width is 4.
Now compare areas:
smaller rectangle would have an area of 18 because length 6 * width 3 is area 18.
larger rectangle would have area 32 because length 8 * width 4 is area 32.
The ratio here is 18:32 which simplifies to 9:16.
If the larger rectangle has area 1440, then the smaller rectangle has area 1440 * 9/16 = 810.
