There are 50 exercise books in a pack. There are 75 students in the third grade, and each of them bought 4 copies. How many packs of exercise books do I need to buy in total?
一包练习本有50本．三年级有同学75人，每人买4本．一共需要买多少包练习本？
<gadget id="calculator">75 * 4</gadget>
<output>300</output>

<gadget id="calculator">300 / 50</gadget>
<output>6</output>

<result>6</result>