What should I consider in planning for my future career?

Aside form a students id, what is another card a collage student use to obtain discounts

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.

In 313 ad the roman emperor constantine l published the edict of milan, which established a.) paganism was outlawed in the empire. b.) it was illegal for soldiers to be christians. c.) christians were freed from religious penalties. d.) all roman citizens were required to convert to christianity.