nomor 18 tolong bantuin ya

= 2 (panjang + lebar)
= 2 (40 cm + 20 cm)
= 2 (60 cm)
= 120 cm

= [tex] \pi [/tex] x diameter
= [tex] \frac{22}{7} [/tex] x 20 cm
= 62,85 cm

Keliling daerah yang diarsir
=120 - 62,85
=57,2 cm (A)