How to solve this problem solving question?

Question

I probably look like a complete idiot asking this question, but how do you solve these two questions about calculating the perimeter of these circles.

Answer 1

Hint (for Pac-Man): circumference is $80 \,\pi\,$, then deduct $\frac{40^\circ}{360^\circ}=\frac{1}{9}$ of it, then add twice the radius.