Answer:

Step-by-step explanation:

<h3>Hope it is helpful....</h3>
if you notice the triangle on the left-hand-side, it has a base of 8 ft and a height/altitude of 10.
now, the triangular pyramid has 3 of those triangles standing up, and one at the base lying down, so 4 triangles with that base and altitude. So we can simply find the area of all 4 of those triangles, sum them up and that's the area of the triangular pyramid.
![\bf \stackrel{\textit{area of the four triangles}}{4\left[ \cfrac{1}{2}(8)(10) \right]}](https://tex.z-dn.net/?f=%20%5Cbf%20%5Cstackrel%7B%5Ctextit%7Barea%20of%20the%20four%20triangles%7D%7D%7B4%5Cleft%5B%20%5Ccfrac%7B1%7D%7B2%7D%288%29%2810%29%20%5Cright%5D%7D%20)

in case you wonder why we used 105 as LCD,
21 = 3 * 7
15 = 3 * 5
the "3" is common to both denominators, so we "use it once" and our LCD is then 3 * 7 * 5.
Two decimal places to the left or right? If it’s to the right (postitive) then it’s 7037.1 if it’s to the left (negative) then it’s .70371, hope this helped!