The total operating costs of a monorail are paid using a combination of passenger fares and tax revenue. The farebox recovery ratio is the ratio of passenger fares to total operating costs. A
monorail in one city has $69 million in operating costs per year, and uses $30 million from tax
revenue. To the nearest hundredth, what is the farebox recovery ratio for the city?

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.