Truly do need help with question

When an antibiotic is introduced into a culture of 50,000 bacteria, the number of bacteria decreases exponentially. After 5 hours, there are only 30,000 bacteria. a. Write an exponential equation to express the growth function y in terms of time t in hours. b. In how many hours will half the number of bacteria remain? a. The exponential equation is (Round to three decimal places as needed.) b. Half the number of bacteria will remain in hours. (Round to one decimal place as needed.)