Question 1114845
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After folding, you get an open box.


Its base is the square with the side length of (x-2*4) = x-8 cm, where x is the side of the original cardboard.


The height of the box is 4 cm.


Hence,  4*(x-8)^2 = 144  is the volume equation.


It gives  (x-8)^2 = {{{144/4}}} = 36.


Hence,  x-8 = {{{sqrt(36)}}} = 6.


Then x = 6+8 = 14.


<U>Answer</U>.  The side length of the original square piece of cardboard is 14 cm.
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Solved.