How to solve 4 variables I received the below puzzle today (via whatsapp):


  


We tried to solve this, but we can't solve.
We think that this puzzle is wrong.
Can this be solved? Or is this a wrong puzzle?
You can write the unknowns like this:   

$a$ ;       $a-9$
$12-a$ ;    $-2-a$ 

This helps you keep the number of unknowns minimal (just $a$).   

Now the horizontal ones are satisfied and so is the 1st vertical.
Then (from the 2nd vertical) you get  $(a-9) + (-2-a) = 2$ which can never be true.
So this puzzle has no solution indeed.
Considering the top two squares as $a$ and $b$, the bottom squares as $c$ and $d$, then
$$a = 4.5 \\
b = -4.5 \\
c = 7.5 \\
d = 6.5$$