Câu 9: Một thửa ruộng hình thang có đáy lớn 90 m, đáy bé bằng 2/3 đáy lớn , chiều cao bằng một nửa tổng hai đáy. a) Tính diện tích thửa ruộng đó. b) Người ta trồng lúa trên thửa ruộng đó. Biết rằng cứ 100 m2 diện tích của thửa ruộng thì thu hoạch được 60 kg thóc. Hỏi trên cả thửa ruộng đó người ta thu hoạch được bao nhiêu tạ thóc? Bài 10: Tính bằng cách thuận tiện nhất: a) 235,7 – 100 x 0,01 x 235,7 b) 6,13 : 0,5 + 6,13 x 9 – 6,13

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