Natasha and Richard are marking exam papers. Each set takes Natasha 45 minutes and Richard 1 hour. Express the times Natasha and Richard take as a ratio.
Give your answer in its simplest form.​

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?

Ann and betty together have $60 ann has $9 more than twice betty’s amount how much money dose each have

Evaluate the expression for the given value of the variable. | ? 4 b ? 8 | + ? ? ? 1 ? b 2 ? ? + 2 b 3 -4b-8+-1-b2+2b3 ; b = ? 2 b=-2