Adog is given a dosage of 100 mg of antibiotics. the amount of antibiotics in the dog's bloodstream will decrease by 40% each hour over the next 8 hours. which exponential equation models this situation?

Last month, leonhard euler's watch kiosk at the mall had total sales of $9,489. merchandise totaling $225 was returned. the goods that were sold cost leonhard euler's $5,481. operating expenses for the moth were $992. what was the gross profit on sales?