In what ratio must a 40% acid solution and a 70% acid solution be mixed to obtain a 50% acid solution?

एलीगेशन (Alligation) का उपयोग करते हुए: (उच्च - औसत) : (औसत - निम्न) = (70 - 50) : (50 - 40) = 20 : 10 = 2 : 1।