So to find the answer to this, you have to consider that 
- half because half the pocket money (x) was spend on clothes, then plus 9 because that's how much extra she gained and 13 because that was the result of all the changes.
To solve this, first subtract 9 from both side, which leaves you with
and 
is the same as 
, so to solve this, multiply both sides of the equation by two, resulting in 
. SO from this we can conclude that the weekly allowance is $8
To solve this, first subtract 9 from both side, which leaves you with