the sum of 13 consecutive integers is 26. what is the largest of the integer

look at it as an arithmetic series where

a = ? d = 1 and n = 13
S(13) = (n/2)(2a + (n-1)d)
26 = (13/2)(2a + 12)
4 = 2a + 12
2a = -8
a = -4

term(13) = a + 2d = -4 + 12 = 8