PLZ, help me with 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?

The water has been on the stove y=9.5x+62.1 after how many minutes will the tempature be 138.1 f

[15 points, algebra 2]simplify the complex fraction and find the restrictions.