The students in class 305 of Zhenhai Yale went rowing. There were 50 students in the class, and they rented 10 boats in total. Among them, each big boat took 6 people, and each small boat took 4 people. How many big boats were rented?
镇海雅乐305班学生去划船，全班50人，一共租了10条船，其中每条大船坐6人，每条小船坐4人，大船租了多少条．
<gadget id="calculator">4 * 10</gadget>
<output>40</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

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

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<result>5</result>