In the lab, Goran has two solutions that contain alcohol and is mixing them with each other. Solution A is 40% alcohol and Solution B is 10% alcohol. He uses 800 milliliters of Solution A. How many milliliters of Solution B does he use, if the resulting mixture is a 30% alcohol solution?

400milliliters

Step-by-step explanation:

Let x=ml of 30% solution B used in resulting mixture.

800+x=ml of resulting 30% solution

40%(800)+10%x=30%(800+x)

Then we can simplify the expression

0.4(800)+0.10x= 0.30(800+x)

320+0.10x=240+0.30x

80=0.20x

x= 400milliliters

Therefore, 400milliliters of 10% solution B used in resulting mixture.