There are 840 students in the sixth grade and 720 students in the fifth grade. If 40 students are equipped with one computer, how many more computers should the sixth grade have than the fifth grade?
六年级有学生840人，五年级有学生720人，如果40个学生配一台电脑，六年级应比五年级多配多少台电脑？
<gadget id="calculator">840 - 720</gadget>
<output>120</output>

<gadget id="calculator">120 / 40</gadget>
<output>3</output>

<result>3</result>