How did the 5 become 15/4... kinda confuse can anybody help?

Acircle has a circumference of 2 pi cm. which statement about the circumference and area is true? a comparison of the area and circumference is not possible since the area cannot be determined. the numerical values of the circumference and area of the circle are equal. the numerical value of the circumference is greater than the numerical value of the area. the numerical value of the circumference is less than the numerical value of the area.

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

Pat listed all the numbers that have 15 as a multiple write the numbers in pats list