Elon sent a chain letter to his friends, asking them to forward the letter to more friends. The relationship between the elapsed time, ttt, in days, since Elon sent the email, and the total number of people who receive the email, P(t)P(t)P, left parenthesis, t, right parenthesis, is modeled by the following function: P(t)=4⋅3t Complete the following sentence about the daily rate of change in the number of people who receive the email.