tolong pake cara ya, makasih udh bantu.

L bangun = (20×6) + (6×(28-20)) + (28×(21-6-6))
= 120 + (6×8) + (28×9)
= 120 + 48 + 252
= 420 cm^2

luas daerah = (12x6)+(21x8)+(20x9)
= 72+168+180
= 420cm²