Question 255479
Let's call the width W and the length L.  Then we have:

{{{W = 5L - 30}}}

And we know that the equation for perimeter is {{{24=2W+2L}}}.

So using the substitution above, we have:

{{{24 = 2(5L-30)+2L}}}
{{{24 = 10L-60+2L}}}
{{{24 = 12L-60}}}
{{{84 = 12L}}}
{{{7 = L}}}

So the length is 7 feet.  Thus, using our original equation for width, we have a width of 5 feet.