How many ml of a 70% alcohol solution must be mixed with 2 ml of a 85% alcohol solution to make a 75% solution?

0.133 ml

Step-by-step explanation:

The two available solutions to be used in the mixture are a 70% solution and a 85% solution.

x = volume of 70% solution

y = volume of 85% solution

y = 2 ml

Therefore;

0.7 x + 0.85 (2) = 0.75 (x+2)

0.7x + 1.7 = 0.75x + 1.5

multiply through by 10 to get rid of the decimals

7x + 17 = 7.5x + 15

collecting and simplifying

-0.5 x = - 0.2

divide both sides by - 1.5

x = - 0.2/-1.5

x = 2/15 ml or 0.1333 ml