A kind of milk, the store is promoting, buy three get two free, 30 yuan per box, buy 3 boxes at a time, how much does each box actually cost?
一种牛奶，商店搞促销，买三赠二，每箱30元，一次购买3箱，每箱实际用多少钱？
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 * (3/5)</gadget>
<output>18</output>

<result>18</result>