Solve the system by substitution.
-x+8y=20
x=y+8

Easy points boii. read it. ya. fresh

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?

How do i do this activity, is appreciated