# Help with this math problem!!!

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It is from CWP level 5 and I am stumped as to how to visualize it. It is also in the challenging problems set.

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

I can find the width of the original piece of cardboard. I know the cubical box is 12 x 12 x 12 and I know that once I cut out the part to make the cube I use the remaining dimensions to find the area left.

BUT I cannot figure out how to cut out the piece for the cube!!!

Linda

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It doesn't matter where you cut the cube from. The sa of the cube is 6*12*12 so just subtract that from the initial area.

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Why 6*12*12 and not 12*12*12?

Linda

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SA of the cube is the SA of each side, 12*12 times the number of faces, 6. The volume is 12*12*12 but that's not what you're looking for.

Thanks

Linda

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