Round to the nearest whole number 3.1

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

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

The figures below are made out of circles, semicircles, quarter circles, and a square. find the area and the perimeter of each figure and give your answers as a completely simplified exact value in terms of π (no approximations).