The department store bought 5 boxes of thermos cups, 12 in each case, and sold 3 thermos cups on Sunday, earning 39 yuan. If all these thermos cups were sold, how much money would the department store earn in total?
百货商店进来5箱保温杯，每箱12个，星期天卖出了3个保温杯，收进39元，如果这些保温杯全部卖出，百货商店共能收进多少钱？
<gadget id="calculator">39 / 3</gadget>
<output>13</output>

<gadget id="calculator">13 * 12 * 5</gadget>
<output>780</output>

<result>780</result>