Calcula el área y el perímetro de un rectángulo si su base mide x+8 y su altura 9-y

You have a 10x10 square, which means there are 100 total squares, making this problem easier.

Look to the right of the square and count the columns which are full, you get 7 full columns. 7 x 10 = 70. Keep this in mind.

Lastly, you have another 7 single squares. Add both of these numbers up: 70 + 7 and you get 77.

Since there are 100 total squares, you get a fraction of 77/100, which is then converted to 77% of the whole square.

ANSWER: 77%