Im gonna guess 6.00 beacause it says round to hundreths
The answer is c. 
a.
(2.2≠5.11) (2.2 is not equal to 5.11)
b.
or 0.625 (0.625≠5.11) (0.625 is not equal to 5.11)
c.
(5.11=5.11) (5.11 is equal to 5.11)
Therefore c is the answer
1.D 2. A 3.C 4.D
1 Is the monomial as it only contains one expression.
2. Is the difference of squares because something squared minus something squared.
3. Is standard because it is of the form

4. We know D is the not the monomial simply because its power is negative which means it does not fit the definition of a polynomial.
First we have to assume that each quarter touched each other. Hence the area of the table not covered by the coins (A) is equal to the total area of the table (At) minus the total area of the coins (Ac). Coins are circle, so

and r =24.26mm. The area of one coin is then 1848.98mm^2. Hence the equation is A = At - xAc where x is the number of coins.