Question 1089270
u, the width of the frame


{{{(8+2u)(12+2u)-8*12=8*12}}}

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{{{(8+2u)(12+2u)=2*8*12}}}

{{{2*2(4+u)(6+u)=2*2*4*12}}}

{{{(4+u)(6+u)=48}}}, more than one way to go from here to finish


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u=2