Final answer:
The equation solved for the radius in terms of the circumference of a circle is r = C / 2π, which corresponds to option a in the question.
Step-by-step explanation:
The formula to find the circumference (C) of a circle with radius (r) is C = 2πr. To solve for the radius in terms of the circumference, we rearrange the formula to isolate r. By dividing both sides of the equation by 2π, we get the formula for the radius as r = C / 2π, which corresponds to option a in the question provided. Therefore, the equation that shows the formula solved for the radius in terms of the circumference is r = C / 2π.