Hello can someone help me on this question

Acircle has a circumference of 7.850 units. what is its radius?

Need to finish my juan wants to build a greenhouse in his back yard. he needs to maximize the ratio of floor area to structure volume in order to provide the most room for plants while minimizing the area to be heated. find the description of the structure that best meets juan’s criteria. a.) a hemisphere with a diameter of 12 feet b.) a cube with a side length of 12 feet c.) a cone with a diameter of 12 feet and a height of 10 feet d.) a square pyramid with a base side length of 12 feet and a height of 9 feet

Aband wants to create a cd of their last concert. to creat the cds, the cost will be $350 advertisement fee plus $3 per cd. write an inequality that represents how many cds they can buy with a maximum of $1225.solve the inequality