98
480
you add up all the numbers in the sequence then divde your answer by how many numbers there are in the sequance so if you had the numbers 20, 19, 7, 45, 2 you would add them up which equals 93 then divide it by 5 (how many numbers in the sequence) so your answer would be 18.6
37
35
1
5 and -4
5
28
false none of the numbers add up to 31
if you mean what three prime numbers add up to a prime number then the answer is : 5 + 7 + 11 = 23
21
31 and 5