# SOLUTION: A lab tech needs to make a 10 liter batch of antiseptic that is 60% alcohol. How can she combine a batch of 30% alcohol with another that is 70% to make the desired concentration?

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 Question 178652This question is from textbook introductory and intermediate algebra : A lab tech needs to make a 10 liter batch of antiseptic that is 60% alcohol. How can she combine a batch of 30% alcohol with another that is 70% to make the desired concentration? This is in my section on systems of equations. I'm supposed to write a system of equations to solve this problem. I can't figure out how to make a system for this. Can someone please explain how to make a system for this?This question is from textbook introductory and intermediate algebra Answer by Mathtut(3670)   (Show Source): You can put this solution on YOUR website!ok lets call the amount of 30% and 70% batch a and b respectively : x+y=10............eq 1 because there is 10 liters altogether : .3x+.7y=.6(10)....eq 2 : rewrite eq 1 to x=10-y and plug that value into eq 2 : .3(10-y)+.7y=.6(10) : 3-.3y+.7y=6 : .4y=3 : liters of 70% batch : liters of 30% solution