ok so i rlly need help with number 8 and 9. as a class the teacher did 10 and ik she went up by 3’s but why like i just need help (i will make u brainliest)

ok so i rlly need help with number 8 and 9 as a class the teacher did 10 and ik she went up by 3s but why like i just need help i will make u brainliest class=