Hello, crazydaizy78!

You started correctly . . .The antibiotic clarithromycin is eliminated from the body according to the formula:

. .

is amount remaining in mg remaining in body after (t) hours.

How much time will pass before the amount of drug in the body is reduced to 100 mg?

We have: .

Divide by 100: .

Multiply by

Take logs: .

And we have: .

Since , we have: .

. . Therefore: . hours.