Answer:
Let's find the base area:
21 x 9 = 189
Now let's multiply the base area by the height:
189 x 5 = 945
Now let's divide by 3( x 1/3 ):
945 divided by 3(x 1/3) = 315 yd^3 is your answer
Explanation:
Formula area of a rectangular Pyramid(just like any other pyramid):
BH x 1/3
To find base we multiply length by width just using the basic formula of finding area of a rectangle.
Then we multiply our base area by our height.
One we've done that we now divide by 3(multiplying by 1/3)