Dùng một ca múc nước ở thùng nước A có nhiệt độ tA = 20 độ c và ở thùng chứa nước B có nhiệt độ tB= 80 độ c rồi đổ vào thùng chứa nước C. Biết rằng trước khi đổ, trong thùng chứa nước C đã có sẵn một lượng nước ở nhiệt đọ tC= 40 độ c và bằng tổng số ca nước vừa đổ thêm vào nó. Tính số ca nước phải múc ở mỗi thùng A và B để có nhiệt độ nước ở thùng C là 50 độ c. Bỏ qua sự trao đổi nhiệt với bình chứa và ca múc nước giúp mình giải bài này với

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