Answer: 
Step-by-step explanation:

5/7= -----------
0.714285
Convert the fraction to a decimal by dividing the numerator by the denominator.
6/10= 0.6
Convert the fraction to a decimal by dividing the numerator by the denominator.
16/20= 0.8
Convert the fraction to a decimal by dividing the numerator by the denominator.
9/10= 0.9
Convert the fraction to a decimal by dividing the numerator by the denominator.
Let's say side length is s.
s*s = 500, so s = √500.
4 sides needed, total length thus 4*s.
4√500 ≈ 89.4
D.
Because 4 divided by 2 is 2
The points for C is (12, 10.5)