Please HELP
20 POINTS!

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)

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?

Arectangular garden measures 5m by 7m. both dimensions are to be extended by the same amount so that the area of the garden is doubled. by how much should the dimensions increase, to the nearest tenth of a metre?