In essence, this is a linear programming problem, and the thinking is very direct. Four constraints are given in the title.

Suppose you take X pills of medicine A and Y pills of medicine B every day. In addition to the given four constraints, you should also add.

X>0, y>0, so we can give the light green effective area in the figure below, where

Integer points all meet the constraints given in the topic, so it is enough to find the maximum or minimum value in these points. ...

In this process, the most critical step is to give conditional expressions and draw pictures.

The answer is obvious.