The cost, c , of a ham sandwich at a deli varies directly with the number of sandwiches, n If c is equal to 54 dollars when n is 9 , what is the cost of the sandwiches when n is 3 ?

Because the cost varies directly with the number of sandwiches, the cost per sandwich stays constant. At 9 sandwiches, the cost per sandwich is $54 ÷ 9 = $6. For 3 sandwiches, the cost is 3 × $6 = $18, so the correct choice is 18 dollars.

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