What is the common difference in the arithmic sequence 30,27,24,21,18

If you have two terms in a sequence, then a term decreased by the previous term=common difference

so
30 and 27

27 decreased by 30 is -3

the common differce is -3

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)

Ibelieve that c. recording would work best.