F(x)=6(2-x), find f(-9)

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 is the sum of these mixed numbers 4 2/3+ 3 1/9

Bob paid $3 less than tim at a local pizza parlor. together they spent $7.80. how much did bob pay for pizza?