This is the concept of sequences and series; The sum of arithmetic series is given by: Sn=n/2(2a+(n-1)d) n=number of terms a=1st term d=common difference From our sequence; a=6, d=8, n=26 hence; Sn=26/2(2*6+(26-1)8) Sn=13(12+25*8) Sn=13(12+200) Sn=13(212) Sn=2,756 The answer is 2,756
