The fourth-grade students are going to make 80 lanterns, and they have already made 20. The rest will be distributed to 15 students on average. How many lanterns should each student make on average?
四年级同学准备制作80个灯笼，已经做了20个，剩下的平均分给15名同学来完成，平均每名同学要做多少个？
<gadget id="calculator">80 - 20</gadget>
<output>60</output>

<gadget id="calculator">60 / 15</gadget>
<output>4</output>

<result>4</result>