The third and fourth grades had to water 620 trees, and the third grade watered 40 trees a day for 8 days; the rest was watered by the fourth grade in 5 days, how many trees were watered on average every day?
三年级和四年级要给620棵树浇水，三年级每天浇40棵，浇了8天；剩下的由四年级来浇，5天浇完，平均每天浇多少棵？
<gadget id="calculator">40 * 8</gadget>
<output>320</output>

<gadget id="calculator">620 - 320</gadget>
<output>300</output>

<gadget id="calculator">300 / 5</gadget>
<output>60</output>

<result>60</result>