Answer :

mariamikayla
[tex]13x+15=11x-25 \\ \\ 13x-11x=-25-15 \\\\ 2x=-40 \\\\ \boxed{x=-\frac{40}{2}=-20}[/tex]

You pass the free terms wich don't contain 'x' in the othe part of the equal with changed signe ans the same for the terms wich contain x.