Question 1052382
For a rectangle,
{{{P=2L+2W}}}
{{{2L+2W=50}}}
{{{L+W=25}}}
You also know,
{{{L=5+W}}}
Substituting,
{{{5+W+W=25}}}
{{{2W=20}}}
{{{W=10}}}
then,
{{{L=5+10}}}
{{{L=15}}}