I need help, please.

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?

Multiplying an even number of negative numbers gives an answer that is choose from:

How can the correlation in the scatter plot graph below best be described? positive correlation negative correlation both positive and negative no correlation