A school has 30 dormitories, each of which has 6 people in the big dormitory and 4 people in each of the small dormitories. It is known that there are 168 people living in these dormitories, so how many large dormitories are there?
某学校有30间宿舍，大宿舍每间住6人，小宿舍每间住4人．已知这些宿舍中共住了168人，那么其中有多少间大宿舍？
<gadget id="calculator">4 * 30</gadget>
<output>120</output>

<gadget id="calculator">168 - 120</gadget>
<output>48</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">48 / 2</gadget>
<output>24</output>

<result>24</result>