I Love Musical Stars

Answer: $3$

Substitution

Image

  So 2

Image

   are worth 2 more than 2

Image

 

Image

3

Image

  would be worth 2 less ie. 9, so each 

Image

  is worth 3.

Elimination

Consider the third column:

$2$

Image

 $+$ 

Image

 $=13$            $(1)$

and the second row:

Image

  $+ 2$ 

Image

  $=11$          $(2)$

$2 \times (2) - (1)$ yields:

$3$ 

Image

 $=9$

So 

Image

$=3$.