not sure this is the right place

I am a CNA and medication technican. I am going to school to become a pharmacy technican. I also currently work as a med tech.

Calulating pills is not a problem. I can work with all the pill calulations with no problems. I have never worked with iv's or solutions. I am having problems trying to figure out how to calulate for solutions. I am hoping that someone can put in English for me. I read the book, looked at examples and still can not understand what it is they want me to do. Below is (2) examples. Can anyone explain what to do in terms I might understand.

1) Prepare 250 mL of a 24% boric acid solution from 50% boric acid solution and water. How many mL of 50% boric solution will be required?

50% 24

24%

0.9% 26

Determine parts total: 24 + 26 = 50

24 x 250mL = 120mL of 50% boric solution

50

26 x 250mL = 130mL of 50% water

50

(Points: 1)

2) Using 15% and 8% stock ointments, you've been asked to prepare 300 g of a 10% ointment. How many grams of 8% will you need?

15% 2

10%

8% 5

Determine parts total: 2 + 5 = 7

2 x 300g = 85.7g of 15% ointment

7

5 x 300g = 214g of 8% ointment

7

I'm hoping someone knows how to translate this to me in easier terms.

Do I multiply, divide? do I take 300/10=30 or do I take 214/85.7