Answer:
48 cubic yard
Step-by-step explanation:

The area is 1680 ft. squared
It will take her around 126 minutes
You are missing the screenshot I don’t mind helping you please post screenshot
Answer:
All the three statements presented are indeed valid and satisfy the De Morgan's theorem.
Step-by-step explanation:
The truth tables are presented in the attached images.
a) The statement (X + Y + Z)' = (X'Y'Z') has its proof in the first image attached.
b) The statement (XYZ)' = (X' + Y' + Z') has its proof in the second image attached.
c) The statement (X + YZ) = (X + Y)(X + Z) has its proof in the third image attached.