tolong kak besok dikumpulin (bangun campuran) suruh cari luas

L persegi panjang = p x L = 57 x 20= 1140
alas segitiga = 57 - 20- 19 = 18
tinggi = 51 - 20 = 21
L segitiga = 1/2 × a x t = 1/2 ×18 ×21 = 189
L total = 1140 + 189 = 1329