1st : Find the volume of the rectangular block:
12 × 10 × 20 = 2400 cm^3.
2nd : Find the volume of a cylinder

Where r is radius & h is height.
so:

= 76.02654222 cm^3
Lastly, divide the volume of the rectangular block by the volume of the cylinder
2400 ÷ 76.026 = 31.5679226
You can't round it up so the answer is F) 31
The original price of the item is said to be 100 dollars.
Now, it offers 15% discount. Let's solve for the dicounted price.
=> 15% = 0.15
Solution:
=> 300 * .15
=> 45 dollars
=> 300 dollars - 45
=> 255 dollars
By applying 2×pie×radius (radius+height)
This answer comes 1925000mm^3
A)
Since 5 of the books are new, that means that the other books are used. So, there are 11-5=6. The ratio would be 5:6.
b)
The ratio is 6:11. You get the 6 from the above problem.
Hope this helps!