Question 979997
This will be only part-way, and only in symbols.


p, perimeter given, and w for width, L for length;
L=w+5.


{{{2w+2L=p}}}
{{{2w+2(w+5)=p}}}
Solve for w first...


Area A would be  {{{wL=A}}}.


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Try to fill the missing steps according to 
w=17, L=22, and A=374.