Question 1132723
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The volume of the box is the area of the base multiplied by the height.  The height is 3 inches, and the volume is 357 cubic inches; so the area of the base is 357/3 = 119 square inches.<br>
Use mental arithmetic to find two numbers that differ by 10 and whose product is 119.  Those will be the dimensions of the base of the box.<br>
Then, since the box was formed by cutting 3-inch squares out of each corner of the original piece of cardboard, add 6 inches to each dimension of the base of the box to get the dimensions of the piece of cardboard.