\"\"

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Cost of each shirt =  $12.50.

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Total cost of shirts = Cost of each shirt \"\" total number of shirts purchesed by

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each person.

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Total number of shirts purchesed = 2 + 3 + 1.

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Expression for the Total cost of shirts = 12.50( 2 +  3 + 1). \ \ \"\"

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The solution is 12.50( 2 +  3 + 1).