A, B, and C buy a box of hairtail together with the same amount of money. When distributing the fish, A and B both take 3 kilograms more than C. When paying the bill, both A and B pay C 15 yuan. How much is it per kilogram of hairtail? ?
甲、乙、丙三人拿同样多的钱合买一箱带鱼，分配鱼时甲和乙都比丙多拿3千克，结账时甲和乙都要付给丙15元，每千克带鱼多少钱？
<gadget id="calculator">3 + 3</gadget>
<output>6</output>

<gadget id="calculator">6 / 3</gadget>
<output>2</output>

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">15 / 1</gadget>
<output>15</output>

<result>15</result>