Your correct answer is option B
Answer:

Step-by-step explanation:
we know that
The area of the polygon is equal to the area of a square plus the area of four congruent triangles
so
![A=b^2+4[\frac{1}{2}(b)(h)]](https://tex.z-dn.net/?f=A%3Db%5E2%2B4%5B%5Cfrac%7B1%7D%7B2%7D%28b%29%28h%29%5D)
where

substitute
![A=8^2+4[\frac{1}{2}(8)(4)]](https://tex.z-dn.net/?f=A%3D8%5E2%2B4%5B%5Cfrac%7B1%7D%7B2%7D%288%29%284%29%5D)

There are 11 days until Richards's concert.
Susie's concert is 7 days after Richard's.
so Susie's concert: 11+7=18
answer
D. 11+7=18