Solution
Note: Formula To Use
[tex]Area=lw[/tex][tex]\begin{gathered} A=\frac{2x+6}{x+1} \\ \\ A=\frac{2(x+3)}{x+1} \\ \\ l=\frac{x^2-9}{2x+10} \\ \\ l=\frac{(x-3)(x+3)}{2(x+5)} \\ \\ w=? \end{gathered}[/tex]Substituting the parameter
[tex]\begin{gathered} Area=lw \\ \\ \frac{2(x+3)}{x+1}=\frac{(x-3)(x+3)}{2(x+5)}\times w \\ \\ divide\text{ both side by }(x+3) \\ \\ \frac{2}{x+1}=\frac{x-3}{2(x+5)}\times w \\ \\ w=\frac{2}{x+1}\times\frac{2(x+5)}{(x-3)} \\ \\ w=\frac{4(x+5)}{(x+1)(x-3)} \end{gathered}[/tex]Therefore, the width is
[tex]\frac{4(x+5)}{(x+1)(x-3)}[/tex]