Pake cara tolong ya please

Luas setengah lingkaran besar
D = 28 cm
r = D/2 = 28/2 = 14 cm

L = 1/2 . π.r²
L = 1/2 x 22/7 x 14 x 14
L = 1/2 x 22 x 2 x 14
L = 308 cm²

Luas setengah lingkaran sedang
D = 20 cm
r = D/2 = 20/2 = 10 cm

L = 1/2.π.r²
L = 1/2 x 3,14 x 10²
L = 1/2 x 3,14 x 100
L = 157 cm²

Luas setengah lingkaran kecil
D = 8 cm
r = D/2 = 8/2 = 4 cm

L = 1/2.π.r²
L = 1/2 x 3,14 x 4²
L = 1/2 x 3,14 x 16
L = 25,12

Luas daerah yang diarsir
L = 308 - 157 - 25,12 = 125,88 cm²

20:2=10
10×10=100
3,14×100=314:2=157
8:2=4
4×4×3,14=50,24:2=25,12
157+25,12=182,12
28:2=14
14×14×22/7=616:2=308-182,12=125,88