The arithmetic sequence general formula is an = a1 + d *(n-1) where d is the arithmetic difference and n is an integer. In this case, upon derivation, the formula that represents the sum of the series is S = (a1 + an)*(n/2). Substituting, S = (3+75)*(10/2) equal to 390
C. 20/4 because a fraction isn’t a whole number.
(6.0 x 10^5) x (3.0 x 10^4) = (6 x 3) x 10^(5 + 4) = 18 x 10^9 = 1.8 x 10^10
