SOLUTION: Mark has a rectangular cardboard of length 68 cm and perimeter 230cm. He cuts a part of the cardboard to make a cubical box 12cm long. What is the area of the cardboard left?

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Question 699221: Mark has a rectangular cardboard of length 68 cm and perimeter 230cm. He cuts a part of the cardboard to make a cubical box 12cm long. What is the area of the cardboard left?
Answer by pmatei(79) (Show Source):
You can put this solution on YOUR website!
To find the area of the cardboard left, you need to know how much area you had and how much area you cut.
The rectangle area is length times width. We know the length and perimeter which is 2 lengths and 2 widths.

So the area of the rectangle is:

Now lets calculate the area you cut for the cubical box. If the box does not have a lid, then you need 5 squares of side 12 cm. If the box has a lid, then you have a complete cube and you need 6 squares.
I assume it is a box without lid. Then the area is:

Thus the remaining area after I cut enough for the box is:
square cm.