Find the circumference of a pizza with a diameter of 10 inches

Write a positive or negative number to represent each situation. a. you win 150 dollars in a contest b. a loss of 15 yards in a football game c. 75 feet below sea level d. 35 degrees above 0 f e. a debt of 24.75 dollars

Circle a has a diameter of 7 inches, a circumference of 21.98 inches, and an area of 38.465 square inches. the diameter of circle b is 6 inches, the circumference is 18.84 inches, and the area is 28.26 square inches. part a: using the formula for circumference, solve for the value of pi for each circle. (4 points) part b: use the formula for area and solve for the value of pi for each circle. (4 points)

Having a hard time understanding this question (see attachment).