Answer:
25π
Step-by-step explanation:
pi's symbol is π, which will be used sometimes to make it easier later
The circumference is equal to diameter multiplied by pi. (Diameter is the length across the circle, radius the center of the circle to an edge point aka. half the diameter, and circumference is the edge length aka. perimeter of the circle.)
We can then remove the pi off the 10, as the diameter multiplied by pi is the circumference, so the diameter is 10.
Half of 10 is 5, the radius.
The formula for area of a circle is radius squared times pi, remember easily by π r ^2
We can plug in the radius into the formula to get
π 5 ^2
And finish it by solving the square root to get
π 25
25π
Add then I would divide it
Keywords:
<em>System of equations, variables, hardcover version, paperback version, books
</em>
For this case we must construct a system of two equations with two variables. Let "h" be the number of hardcover version books, and let "p" be the number of paperback version books. If the hardcover version of a book weighs 7 ounces and the paperback version weighs 5 ounces, to reach a total of 249 ounces we have:
(1)
On the other hand, if there are Forty-five copies of the book then:
(2)
If from (2) we clear the number of books paperback version we have:

As each paperback version book weighs 5 ounces, to obtain the total weight of the paperback version books, represented by "x" in the table shown, we multiply
So, 
Answer:

Option D
I completely forgot how to do this but maybe multiply the angles I’m so sorry