I guess you are asking to find the sum of the first 8 terms. If so, then:
Sum = a₁(1-rⁿ)/(1-r), where a₁ is the 1st term, r=common ratio and n=number of terms:
the 1st term a₁ =3
common ratio r = - 2 (since -6/3 = - 2, and 12/-6 = - 2, etc.)
Sum = 3[(1- (-2)⁸]/(1-2) = 3(1- 256)/(1/2)
Sum = -1530
Given
GO.o has 3 orange picks for every 2 green
there are 25 picks in all
Find out how many picks are orange.
To proof
As given in question
GO.o has 3 orange picks for every 2 green
i.e the ratio of orange to every green becomes

total number of picks = 25
let the GO.o pick of 3 orange picks for every 2 green =x
than the equation becomes
3x + 2x = 25
5x = 25
x = 5
Than
the number of oranges = 3x
putting the value of x
= 15
the number of green = 2x
= 10
thus the 15 picks are orange.
Hence proved
The answer would be 2. You have to do multiplication first.