Your answer is 560cm^2.
We get this answer first by dividing 96 by 2, because the perimeter is made up of 2 lots of both sides. This gives us 48cm.
Then we find out how long each side is by adding together 5 and 7 to give us 12, and dividing 48 by 12 to give us 4. This is how big each of the 'parts' of the ratio are. Then, we just multiply 4 by 5 to get 20, and 4 by 7 to get 28.
This tells us that 20 and 28 are the side lengths, so we just need to multiply them together to get the area of the rectangle, which gives us 560cm^2.
I hope this helps! Let me know if you have any questions :)
