This is а free-respоnse prоblem, meаning it requires yоu to show your hаndwritten work and will be graded for partial credit. You do NOT need to enter anything in the text box below. Instead, at the end of the exam, you will be asked to upload your written work (which should include the final answers) for all of the free-response problems. ------------------------------------------------------------- The amount (A) of antibiotic (in mg) in a patient's bloodstream is modeled by $$A(t) = 60e^{-0.42t},$$ where (t) is the time (in hours) since the patient received the injection. When will the amount of antibiotic in the patient's bloodstream be 20 mg? Round your answer to one decimal place.