Kayla held a pole in the swimming pool. The bottom of the pole was at a depth of 3 feet. How should Kayla mark the level of the bottom of the pole on the number line? Explain how you determined this. (4 points)

Raul has one solution that is 20% acid by volume and one solution that is 50% acid by volume. he plans to mix together some of each solution to create 30 milliliters of a solution that is 40% acid by volume. how many milliliters of the 20% acid solution should raul use to create the 40% acid solution? can someone explain this to me? i know that the answer is 10 milliliters, but i don't know how to get it.