$\"\"$

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The given masses are $\"\"$ ,

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the coordinates are $\"\"$ .

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The moment of the x - axis is:

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$\"\"$

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$\"\"$ (Substitute)

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$\"\"$ (Multiply)

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$\"\"$ (Add)

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$\"\"$

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The moment of the y - axis is:

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$\"\"$

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$\"\"$ (Substitute)

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$\"\"$ (Multiply)

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$\"\"$ $\"\"$ (Subtract)

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$\"\"$

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The sum of the masses is:

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$\"\"$

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$\"\"$ (Substitute)

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$\"\"$ $\"\"$ (Add)

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$\"\"$

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Therefore center of the mass is:

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$\"\"$ (Center of the mass)

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$\"\"$ (Substitute)

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$\"\"$

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The center of the mass of the given system of points is $\"\"$ .