Hi there!
First Question -
I've attached an image of a net for a triangular prism below. So, let's work on finding the surface area! First, we know that we have two triangles for the bases, so the area of the bases is: 2(1/2(6*8) = 48. Then, we need to find the lateral area: 2(12 x 10) + 1(8 x 12) = 336. Lastly, all we need to do is add the values together: 336 + 48 = 384ft^2.
Second Question -
The second image (a box) represents the room. Here, we are only finding the lateral area. Since we know that we are not painting the floor, that portion is shaded. Here's how we'd find the surface area: 2(15 x 10) + 2(12 x 10) = 540ft^2.
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!