Question 890629
The combined area of picture with border using some unknown width w, is
total area, {{{(2w+16)(2w+20)}}}.


The difference between total area and picture area must be 352 square inches:
{{{highlight_green((2w+16)(2w+20)-16*20=352)}}}.


The simplest first simplification is eliminate a factor of 4:
{{{highlight_green((w+8)(w+10)-4*20=88)}}}
and then
{{{(w+8)(w+10)=88+80=168}}}
{{{highlight_green((w+8)(w+10)=168)}}}



You can finish the arithmetic.