I NEED HELP ASAP PLZZZZZZZZ 20 POINTS AND BRAINLY
A chemistry teacher needs to make a 42% sulphuric acid solution. The acid solutions available are 4 liters of 30% sulphuric acid and 50% sulphuric acid, by volume. How many liters of the 50% sulphuric acid solution must be mixed with the 4 liters in order to make the 42% sulphuric acid solution?