Here, as I can see, you are adding fractions, and making sure you have a common denominator.
12) is correct
13) is correct
You got a common denominator, and added them up! Great job! <span />
An operation that is done to a value and it stays the same, it is called the "identity property".
Some quick examples:
Adding any number with zero will result in the same number.
Multiplying any number with one will result in the same number.
Hope this helps!
Perimeter is the lengths of the edges added up. And if the shape is a rectangle, there are 4 edges so we divide by 4. 44/4=11. each of the four sides are 11 feet long.
width=11
length=11
area=width*length=121
