You need a 30% alcohol solution. on hand, you have a 150 ml of a 10% alcohol mixture. you also have 40% alcohol mixture. how much of the 40% mixture will you need to add to obtain the desired solution?

We have 150 ml of 10% alcohol.How much 40% alcohol must be added to make a 30% solution?
.10 * 150 + .40x = .30 * (150 + x)15 + .40x = 45 + .3x.10x = 30x = 300 ml of 40% alcohol must be added to make a 30% alcohol solution.
Source:http://www.1728.org/mixture.htm