Can someone please help me answer this Math problem?

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

Which part of a 2-column proof is the hypothesis of the conjecture? a) given b) reasons c) prove d) statements ! i think it's b but i'm not quite

What is the 9th term in the geometric sequence described by this explicit formula? an=-6. (2)(n-1) apex