Answer: 506 square units (answer choice B)
Explanation:
The formula for the surface area of a triangular prism is:
SA = bh + 2ls + lb,
where b is the base, h is the height, l is the length, and s is the side of the triangle.
In this case, the base is 7 (Y), the height is 8 (h), the length is 18 (Z), and the side of the triangle is 9 (X).
So, by subsituition, we have:
SA = (7)(8) + 2(18)(9) + (18)(7)
SA = 56 + 324 + 126
SA = 506
The surface area is 506 square units.
Hope this helps! :)