Let's review the information provided to answer the execise correctly:
Strength of the solution = 25 mg per mL
Dosage to prepare = 300 mL
Now, let's answer the question, as follows:
Amount of solution needed = Dosage to prepare/Strength of the solution
Substituting with the values we know:
Amount of solution needed = 300/25
Amount of solution needed = 12 mL
Interpretation
We need 12 mL of solution for a dosage of 300 mg of strength for the patient