Assume that both
Solution A & Solution B have 100 units
Since the ratio in solution A is 21:4, there will be 84 units of Alcohol, to 16 units of Water.
Similarly, solution B will have ratio 2:3(40 units Alcohol:60 units water)
Since the solutions are to mixed in the ratio 5:6(we are adding 500 units of Solution A and 600 units of Solution B)
Total concentration of Alcohol : \(\frac{84*5 + 40*6}{100*5 + 100*6} = \frac{420+240}{1100} = \frac{660}{1100} = 60%\)(Option C)
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