What fraction of the original drug dose remains in the bloodstream in 24 hour?

Your doctor prescribed you to take 300 mg of a pain-relieving drug after you had surgery. The amount of the drug in your bloodstream decreases at a rate of 14% per hour. If you take 300mg of the pain-reliever, how much of the drug will still be in your bloodstream after 7 hours? Round tothe one decimal.

a cup of coffee has 95mg of caffeine. the amount of caffine in your body diminishes by 7% each hour. how kuch caffeine will remain after 4 hours. round to the nearest mg.

The value of a currency appreciated by 7.80% of its value last month and then depreciated by 7.80% this month. By what percent did the currency appreciate or depreciate over the 2-month period?