Yang Yang bought 3 packs of potato chips and 2 boxes of chocolates at the store, spending a total of 13.2 yuan. It is known that each pack of potato chips is 1.8 yuan. How much is each box of chocolates?
杨洋在商店买了3包薯片和2盒巧克力，共花钱13.2元，已知每包薯片1.8元，每盒巧克力是多少元？
<gadget id="calculator">1.8 * 3</gadget>
<output>5.4</output>

<gadget id="calculator">13.2 - 5.4</gadget>
<output>7.8</output>

<gadget id="calculator">7.8 / 2</gadget>
<output>3.9</output>

<result>3.9</result>