Ireally need guys what is the verbal expression for these i made this question

Bismuth-210 is an isotope that radioactively decays by about 13% each day, meaning 13% of the remaining bismuth-210 transforms into another atom (polonium-210 in this case) each day. if you begin with 233 mg of bismuth-210, how much remains after 8 days?

Plzzz i beg u so much asap ! what is the slope of this line? enter your answer in the box.

If you answer right ill give brainliest, : )