If a dosage d of a drug is administered to a patient, the amount of the drug remaining in the tissues t hours later will be f(t) = dekt, where k (the "absorption constant") depends on the drug.t For the cardioregulator digoxin, the absorption constant is k = 0.018. For a dose of d = 7 milligrams, use the previous formula to find the amount remaining in the tissues after the following amounts of time. (Round your answers to two decimal places.) (a) 48 hours (b) 72 hours mg mg