Teacher Yuan had to correct homework. He corrected 18 books on the first and second days respectively, and a total of 44 books on the third and fourth days. How many books are corrected on average per day?
袁老师要批改作业，第一天和第二天各批改了18本，第三天和第四天共批改了44本，平均每天批改多少本？
<gadget id="calculator">18 + 18 + 44</gadget>
<output>80</output>

<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<result>20</result>