If the price is 82 and the sale price is 65.60 how much is the percent of discount

Initially 100 milligrams of a radioactive substance was present. after 6 hours the mass had decreased by 4%. if the rate of decay is proportional to the amount of the substance present at time t, find the amount remaining after 24 hours. (round your answer to one decimal place.)

Answer this question only if you know the answer! 30 points and

Anyone know? will mark brainliest if you're correct!