If we now that 4y equals to x, that means we can replace x with 4y.
Therefore we can write: 4y+2y = 12
We can summarize that to 6y = 12.
If we divide both sides with 6, you get y = 2
In order to solve for x, we can use the second equation and just replace y with value we just got (y=2).
We can write: x+2*2=12
Now you move 2*2 (which is 4) to the other side: x=12-4
Now you get: x = 8
ANSWER

EXPLANATION
The given geometric sequence is
400, 200, 100...
The first term is

The common ratio is

The nth term is

We substitute the known values to get;




Answer:
2(8-d)
Step-by-step explanation:
Because it says 2 times the difference this means the difference will be multiplied by 2. It also says difference which means that 8 and d must be subtracting
2) 100
3) 49
4) 19
5) idk
6) idk
7) 7