Answer:
144
Step-by-step explanation:
20×12=240
add 4 to 20 and 12
makes a new rectangle 24×16
24×16=384
384-240=144
If you draw a picture you can see that the kite, Anna and Emily form a right triangle.
so you can use the pythagorean theorem to find the answer.

1,225 + b^{2} = 2,500
b^{2} = 1,275
b = 35.7 meters
The answer is plane because it is a two dimensional figure