What words match the expression 3+(4x12)

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?

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

Which word in the sentence below is an interrogative pronoun? who is picking us up from school? whousisfrom