Which describes one way that Aristarchus's explanation of the movement of objects in the sky was different from other scientists' earlier explanations?

When creating visuals, a journalist should

When amy exercises in her fitness center for 1 hr she burns a total of 475 calories. if she burns 9 calories a minute jogging on the treadmill and then burns 6.5 calories a minute pedaling on the stationary bicycle how many minutes of the hour does she spend exercising on the bicycle?

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.