First one:
The circumference of the whole circle is (2π x the radius),
and 60° is (60/360) = 1/6 of the whole circumference.
Second one:
The area of the whole circle is (π x the radius²), and
the 40° sector is (40/360) = 1/9 of the whole area.
I hope this is enough help.
I’m not sure if this is how you do it but:
2(8a - 12)
4(4a - 6)
8(2a - 3)
??
