Move n terms on one side and other terms on the other side. Note that by moving we are essentially subtracting and adding to both sides so the prefix of a term changes from - to + or from + to -.
[tex]
-4n-5=-3n+4 \\
-4n+3n=4+5 \\
-n=9 \\
n=-9
[/tex]
Hope this helps.
