Explain how i find the surface area and the answer

You can take it apart. There are a top and bottom (both the same) right triangle. So you can find the area of that by multiplying 8*6 and divide by two. Then multiply by two because there are 2 triangles.
You are left with three rectangular sides: One 10x10, one 10x6, and one 10x8.
So your whole equation looks like this: A = 2[(8*6)/2]+(10*10)+(10*6)+(10*8)

$30

Step-by-step explanation:

6 • 1/3 = 18

18 • 1/2 = 36

36 - 6 = 30