A construction company hired workers. In order for the workers to come to work every day, they signed a contract with the workers: they would get 48 yuan for each working day; the workers had to return 12 yuan to the company every day they did not work. After 30 days, all the workers who signed the contract did not get a penny. So, in these 30 days, how many days did they work?
一个建筑商雇佣工人，为了让工人每天都必须来上班，他们与工人签订了这样的合同：每劳动一天，得48元；不工作的日子，工人每一天必须退给公司12元．30天以后，所有签了合同的工人们没有得到一分钱．那么，这30天中，他们劳动了多少天．
<gadget id="calculator">12 * 30</gadget>
<output>360</output>

<gadget id="calculator">360 + 0</gadget>
<output>360</output>

<gadget id="calculator">48 + 12</gadget>
<output>60</output>

<gadget id="calculator">360 / 60</gadget>
<output>6</output>

<result>6</result>