The perimeter of the circle is also known as the circumference that said figure out what the diameter is and multiply that by pi (3.14)
If he fills 5.9 bags for 18 hours, he will have filled a total of 106.2 bags
The equation is a scientific law, Newton's Law of Gravity,

This is a pretty bad question. Newton's Law of Gravity is a mathematical model of gravitation, originally a theory, verified by observation, and now superseded by the General Theory of Relativity.
C is probably the best answer to this poor question.