Answer :
Consider the first blank is the green box.
Given:
The equations are
[tex]3x+2y=9[/tex]
[tex]-x-2y=4[/tex]
To find:
The value belongs in the green box
Solution:
We have,
[tex]3x+2y=9[/tex] ...(i)
[tex]-x-2y=4[/tex] ...(ii)
Adding (i) and (ii), we get
[tex]3x+2y-x-2y=9+4[/tex]
[tex](3x-x)+(2y-2y)=13[/tex]
[tex]2x+0=13[/tex]
So, the value for the first black is 2x. It means the value belongs in the green box is 2x.
The values of three blanks are 2x, 0 and 13 respectively.
Therefore, the correct option is B.