With a problem like this, set up a proportion (like when making lemonade from a mix).
[tex] \frac{weight}{medicine} = \frac{weight}{medicine} [/tex] is our proportion.
We fill in the the two weights and the 24 grams of medicine in the proportion and solve for the fourth piece not there.
[tex] \frac{150}{24} =\frac{120}{M}[/tex]
We shorten medicine to M and we solve for M by cross multiplying.
[tex] 150M = 2880 [/tex]
[tex] M = \frac{2880}{150} = 19.2 grams [/tex]
The woman should get 19.2 grams of medicine.
