Question 983408
w for width
L for length


{{{L=w+3}}}

Length of printing, {{{L-2*1}}}
Width of printing, {{{w-2(3/2)=w-3}}}


Printed Area, {{{(L-2)(w-3)=80}}}
Substitute for L.
{{{(w+3-2)(w-3)=80}}}
{{{(w+1)(w-3)=80}}}
{{{w^2-2w-3-80=0}}}
{{{highlight_green(w^2-2w-83=0)}}}-----not seem factorable.


Discriminant:  {{{4+4*83=336}}}
{{{336=12*28=2*2*3*4*7=2^4*3*7=2^4*21}}}


{{{w=(2+- sqrt(2^4*21))/2}}}

{{{w=(2+- 4*sqrt(21))/2}}}

{{{w=1+- 2sqrt(21)}}}

Only the PLUS form can be accepted.
{{{highlight(highlight(w=1+2sqrt(21)))}}}
Find L from this value for w.