Please help most tutors are getting concept wrong

Espan The number of bacteria in a culture decreases according to a continuous exponential decay model. The initial population in a study is 400 bacteria, and there are 140 bacteria left after 17 minutes. ? (a) Let t be the time (in minutes) since the beginning of the study, and Olno let y be the number of bacteria at time t. Write a formula relating y to t. X Use exact expressions to fill in the missing parts of the formula. Do not use approximations. D y = DJe Di Aa M (b) How many bacteria are there 21 minutes after the beginning of the study? Do not round any intermediate computations, and round your answer to the nearest whole number. bacteria