Type A sugar in the store is 12 yuan per kilogram, and the kindergarten buys both types of sugar and shares it at 280 yuan. It is known that the number of kilograms purchased for type A sugar is twice the unit price of type B sugar, and the number of kilograms purchased for type B sugar is exactly (1/3) the unit price of type A sugar. How much is the difference between the unit prices of type A and B sugar? ．
商店中甲种糖每千克12元，幼儿园购买甲、乙两种糖共用去280元．已知购买甲种糖的千克数是乙种糖单价数的2倍，购买乙种糖的千克数正好是甲种糖单价的(1/3)，甲、乙两种糖的单价相差多少元．
<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">12 * (1/3)</gadget>
<output>4</output>

<gadget id="calculator">24 + 4</gadget>
<output>28</output>

<gadget id="calculator">280 / 28</gadget>
<output>10</output>

<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<result>2</result>