As the dose is 2 times a day then the first thing we should do is calculate the number of milligrams per day:
![(200) * (2) = 400 mg](https://img.qammunity.org/2019/formulas/mathematics/high-school/jcfakkn7w1xv5dl4216c1cfmtsxapq5vk5.png)
Then, we can make the following rule of three:
300 mg --------> 5 ml
400 mg --------> x
From here, we clear the value of x.
We have then:
Answer:
6.67 ml are needed for one dose