Answer:
70 vials
Step-by-step explanation:
Assuming the proportion holds, ...
... vials/people = x/875 = 4/50
Multiplying by 875, we get
... x = 875·4/50 = 70
70 vials are neede to treat 875 people.
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If the vials only come in packages of 4, then 72 vials (18 packages) are needed
