The perimeter of a rectangle is given by the formula below
[tex]P=2l+2w[/tex]Furthermore, we know that the length is 8 feet longer than the width; this is
[tex]\begin{gathered} l=w+8 \\ \text{and} \\ P=180 \end{gathered}[/tex]Therefore,
[tex]\begin{gathered} \Rightarrow180=2l+2w \\ \Rightarrow180=2(l+w) \\ \Rightarrow90=l+w \\ \Rightarrow90=(w+8)+w \\ \Rightarrow2w=82 \\ \Rightarrow w=41 \end{gathered}[/tex]The width is equal to 41 ft; thus,
[tex]\begin{gathered} \Rightarrow l=41+8=49 \\ \Rightarrow l=49 \end{gathered}[/tex]Therefore, the length of the garden is equal to 49 ft.