This is kind of a tricky question as your reaction will be, well -14v and 14v add up to 0, so I can't really solve for v. But, you are kind of on the right track. If we do the above thing:
[tex]-10 = -14v+14v[/tex]
Then, we get:
[tex]-10=0[/tex]
And we know that:
[tex]-10 \neq 0[/tex]
So, we can conclude that this problem has no solutions. Meaning that there are no values of v that make the equation true.