I got the answers right but i just want know how i got them right . Please explain with steps

A common inhabitant of human intestines is the bacterium Escherichia coli. A cell of this bacterium in a nutrient-broth medium divides into two cells every 20 minutes. The initial population of a culture is 55 cells. (a) Find the relative growth rate. (Assume t is measured in hours.) \"-\"I (b) Find an expression for the number of cells after t hours. (c) Find the number of cells after 8 hours. ink x f 922,746,880 cells (d) Find the rate of growth after 8 hours. (Round your answer to three decimal places.) 1w x Your answer cannot be understood or graded. More Information if 1.919 billion cells per hour (e) When will the population reach 20,000 cells? (Round your answer to two decimal places.) wq x If. hr