algebra problem

How many liters of a 40% acid solution should be mixed with 8 liters of a 25% acid solution to obtain a solution that is 30% acid?

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$x\cdot 40\%+ 8\cdot 25\%=(x+8)\cdot 30\%$

$0.4x+0,25\cdot 8=0.3x+0.3\cdot 8\\ 0.1x=2.4-2\\0.1x=0.4$

$x=4$

4 liters of a 40% acid solution should be mixed with 8 liters of a 25% acid solution to obtain a solution that is 30% acid?

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