The original dimensions of the cardboard is 21 cm × 21 cm, if a square pieces with lengths of sides of 6 cm were cut out of corners of a square piece of cardboard and the volume of the resulting box is 486 cubic centimeters.
Step-by-step explanation:
The given is,
 Square pieces with lengths of sides of 6 cm were cut out of corners of a square piece of cardboard.
 The volume of the resulting box is 486 cubic centimeters.
Step:1
 The volume, is the given piece of cardboard was folded into an open box, we calculate side value of cardboard after cut into a square piece,
 Formula for volume of cardboard is,
 
 ......................(1)
......................(1)
 Where, w - width
 h - Height
 l - length
 From given, V= 486 cubic centimeters
 h = 6 cm ( Ref attachment)
 w = l
 Equation (1) becomes,
 

 

 Take root on both sides
  l = 9 centimeters
Step:2
 Ref the attachment,
 Side value of piece of cardboard
 = 6 + 9 + 6
 = 21
 Side value of piece of cardboard = 21 centimeters 
 original sides of cardboard is 21 cm × 21 cm 
Result:
 The original dimensions of the cardboard is 21 cm × 21 cm, if a square pieces with lengths of sides of 6 cm were cut out of corners of a square piece of cardboard and the volume of the resulting box is 486 cubic centimeters.