Answer: D40% HCL is mixed with 60% HCL in the ratio 4:1 to get 44% hcl.44% and 32% are mixed in the ratio 2:1
Thus the average, we have (x32)/(44x) =2/1 => x=40%.
i.e 50 L of water has been added to a certain quantity of 40% hcl to get 20% hcl. The quantity has to be 50 L. Before the 25L was removed the quantity was 75 L. This, we got by mixing 25L of 32% hcl with 50% L of 44% hcl.
The 44% hcl is got by mixing 40% hcl and 60% hcl in the ratio 4:1. i.e 40L of 40% and 10 L of 60% hcl.
The data and calculations are tabulated below:
Strength (%)

40 
44 
60 
Strength (%) 
40 
44 
60 
Ratio of quantities

4 
5 
1 
Quantity 
40 
50 
10 
Strength (%) 
32 
40 
44 
Strength (%)

32 
40 
44 
Ratio of quantities

1 
3 
2 
Quantity 
25 
75 
50 
Strength (%)

0 
20 
40 
Strength (%)

0 
20 
40 
Ratio of quantities

1 

1 
Quantity 
50 

50 