Asking for some help on 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?

What dimensions can créate more than one triangle ?

In which direction does the left side of the graph of this function point? f(x) = 3x3 - x2 + 4x - 2