How many liters of pure acid must be added to 3 liters of a 50% acid solution to obtain a 75%acid solution?

.75(x+3)=.5(3)+x

You already have 3 liters, and you are going to add x liters.

50% (.5) of the 3 liters is acid, and 100% (1) of the added x liters is acid. You will end up with (3+x) liters.

If you have been assigned this problem, you should be able to solve this equation...

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