The small gear rotates 400 revolutions per minute, the number of revolutions per minute of the large gear is less than that of the small gear (4/5), how many revolutions per minute does the large gear make?
小齿轮每分钟转400周，大齿轮每分钟转的周数比小齿轮少(4/5)，大齿轮每分钟转多少周？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">400 * (4/5)</gadget>
<output>320</output>

<gadget id="calculator">400 - 320</gadget>
<output>80</output>

<result>80</result>