EMERGENCY! Please give me the correct answer!

In the figure shown below, m < 40 and ab =8. which equation could be used to find x?

How long must $542 be invested at a rate of 7% to earn $303.52 in interest? in a easier way

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)