I apologize for my mistake in the previous response.
To scale the photo from 6 cm by 4 cm to fit within a postcard that is 15 cm long, we need to maintain the aspect ratio of the original photo. This means that we adjust both the length and width of the photo by the same scaling factor.
The scaling factor is determined by dividing the length of the postcard by the length of the original photo:
scaling factor = 15 cm / 4 cm = 3.75
Then, we multiply both the length and width of the original photo by the scaling factor to find the dimensions of the scaled photo:
length = 6 cm x 3.75 = 22.5 cm
width = 4 cm x 3.75 = 15 cm
The area of the postcard is then:
area = length x width = 22.5 cm x 15 cm = 337.5 cm²
Therefore, the area of the postcard will be 337.5 cm².