Which describes the set of even numbers between one and eleven?

If you mean all the even numbers that is in between than yes it is 2 4 6 8 10 all you have to do is count by 2s to get all even numbers.

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)