Answer:
21 tablets.
Step-by-step explanation:
28/4=7. 7*3=21.
<em>Hope this helped.</em>
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21 tablets
Do 28/4 which will be 7 tablets per 1/4 of the class, so since she only has enough for 3/4 of the class you need to do 7 tablets times 3 which makes 21 tablets for 3/4 of her class.
13.7142857143
If you need to round then do so, or i will comment the rounded version if needed.