A and B jointly wholesale a basket of apples with the same money. When sharing the apples, A takes 6 kg more than B. As a result, A has to pay B 12 yuan more. What is the unit price of apples per kilogram?
甲、乙两人用同样的钱合着批发一筐苹果，分苹果时甲比乙多拿6千克，结果甲要多付给乙12元，问每千克苹果的单价是多少元．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<result>4</result>