Question 1176832
Cut x at each corner and then  after folding up the flaps,


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{{{x(14-2x)^2=144}}}

{{{x*2*2(7-x)^2=3*4*12}}}

{{{x(7-x)^2=3*12}}}

{{{x(7-x)^2=3*3*4=4*3*3}}}--------comparing left and right members x=4 and 7-x should be 3.


{{{highlight(x=4)}}}