hai pake rumus yah........

bangun 1 (paling atas)
L = 72 x 52 = 3.744 cm2

bangun 2
L = 124 x 48 = 5.952 cm2

bangun 3 (segi3)
L = 1/2 x 32 x 100 = 1.600 cm2

Luas gabungan
3.744 + 5.952 + 1.600 = 11.296 cm2 (B)