Answer:
Patient A receive 150 milligrams and Patient B receive 50 milligrams. 
Explanation:
A patient A receives 3 times the amount of certain medicines patient B.
Let us suppose x milligram of medicine receive by B 
Amount of medicine receive by A= 3x 
Total doses receive by A and B is 200 milligrams. 
Therefore, A+B=200
3x+x=200
Solve for x 
4x=200
x=50 Milligrams 
Thus, Patient A receive 150 milligrams and Patient B receive 50 milligrams.