So basically for the circumference you use C= d×π which means that the circumference is equal to the diameter (radius times 2) multiplied by pi! For the area you use the formula A= r^2×π which means the radius squared (radius times itself) multiplied by pi! By the way you can also round pi down to 3.14 to make it easier. Anyway I hope this helps!!
Im pretty sure he earned 495 in interest, because you take 5,500 time .03 (from the three percent) and you get 165- then multiply by three because of the three years (495)
