C= pi•diameter. If the dinner plate's diameter is 7 inches, then multiply 7 times pi, 3.14. 7•3.14= 21.98. So, the answer for the first question is B, 22. :)
For the second question, it is asking for the answer in terms of pi. Since the diameter is 6, divide 6 by 2 to get the radius. (A=pi•radius squared) 6 divided by 2 is 3. Now, square 3. which gives you 9. Since the answer has to be in terms of pi, the answer is B. ;)
If it is a rectangular prism, then it is 5×2×8, which is 10, from the 5×2 and 8. 10×8 is 80. So the final answer is 80 units cubed. Hope this helps! If you are still confused, please comment so I can help you!
