dianela

if a3= 17 & a8=37 are terms in annarithmetic sequece, fina a1 & d. the answer is a1=9 & d=4 but i don't understand how they got the answer, please help!

march madness is a tournament of the top 64 NVAA basketball teams. at the end of each round there are half as many teams as there were the previous round. there are 6 rounds total. at the end of the tournament, how many games have been played?