Explanation:
Let 'L' be the length, 'W' be the width.
The length is 4 times the width:
[tex]L=4W[/tex]The perimeter of a rectangle is the sum of the sides, which is twice the length plus twice the width:
[tex]2L+2W=45[/tex]Rewriting the first equation with both variables L and W on the same side:
[tex]L-4W=0[/tex]Answer:
The system of equations is:
[tex]\begin{cases}L-4W=0 \\ 2L+2W=45\end{cases}[/tex]