Start from a number x.
If you multiply it by 4 you get 4x.
Then, you add 136 to get 4x+136.
On the other hand, if you start with the same number and multiply it by 9, you get 9x.
Subtract 9 and you get 9x-9.
These two procedures get the same result, so we have
[tex]4x+136=9x-9[/tex]
Subtract 4x from both sides to get
[tex]136=5x-9[/tex]
Add 9 to both sides to get
[tex]145=5x[/tex]
Divide both sides by 5 to get
[tex]x=\dfrac{145}{5}=29[/tex]
