Question 1098839
{{{W=3L-16}}}
and
{{{A=LW}}}
{{{LW=35}}}
Substituting,
{{{L(3L-16)=35}}}
{{{3L^2-16L-35=0}}}
{{{(L-7)(3L+5)=0}}}
Only positive values make sense for the length,
{{{L-7=0}}}
{{{L=7}}}{{{ft}}}
Now use either equation to solve for W.