The rate at which a drug leaves the bloodstream and passes into the urine is proportional to the quantity of the drug in the blood at that time. If an initial dose of Q₀ is injected directly into the blood, 20% is left in the blood after 3 hours.
(a) Write and solve a differential equation for the quantity, Q, of the drug in the blood after t hours.
(b) How much of this drug is in a patient’s body after 6 hours if the patient is given 100 mg initially?