Given
[tex]-8+3v-5-4v[/tex]To simplify this expression you have to order the like terms together, that is, the terms with the variable "v" together and the constants together.
[tex]3v-4v-8-5[/tex]And simplify them by solving the operations between them
[tex]\begin{gathered} (3v-4v)+(-8-5) \\ -v-13 \end{gathered}[/tex]The solution is
[tex]-v-13[/tex]