[tex]\huge\boxed{\text{There is no error.}}[/tex]
Note: I have checked my work multiple times. Consider informing your teacher of this.
We have [tex]\frac{10n-5}{5}[/tex] to start.
Factor out [tex]5[/tex] from the top expression. [tex]\frac{5(2n-1)}{5}[/tex]
Cancel out the [tex]5[/tex]s. [tex]2n-1[/tex]
[tex]2n-1=2n-1[/tex]
