Answer :
[tex]4n+9=6\ \ \ \ \ \ \ \ \ |subtract\ 9\\\\4n=6-9\\\\4n=-3\ \ \ \ \ \ \ \ |:4\\\\n=-\frac{3}{4}[/tex]
-- Subtract 9 from each side of the equation.
-- Divide each side by 4 .
-- The value of 'n' is right there, and you did it all on your own !