The total S divided by 8 was 5 more than the if the total S was divided by 10.
So we have S/8 +5 = S/10 and by switching the equation around you get S/10 = S/8+5
The correct answer is B.
Step-by-step explanation:
in a geometric sequence there is a constant factor x that is multiplied with every previous term to create the next one.
a2 = 20
a5 = 1280 = a2×x×x×x = a2×x³ = 20x³
64 = x³
x = 4
=> a1 = 5
therefore
an = an-1×4 =

n > 1
You can either round to 1000 or 2000 but 1.120 is closer to 1000
7(5)-12(5)-5=-45+15
-30 = -30
answer= B. x=5