Given that amount of first acid solution = 4 liters
Let concentration of the first acid solution = x
then effective amount of first solution = 4x
Given that amount of second acid solution = 10 liters
Givn that concentration of the second acid solution = 40% = 0.4
then effective amount of second solution = 0.4(10)
Then amount of resulting acid solution = (4+10) liters
Givn that concentration of the resulting acid solution = 30% = 0.3
then effective amount of resulting solution = 0.3(4+10)
Combining all those results gives equation
4x +0.4(10) = 0.3(4+10)
4x +4 = 0.3(14)
4x +4 = 4.2
4x = 0.2
x=0.05
Hence final answer is 0.05 or you can say 5%.
