The students made a batch of small toys for the kindergarten children. The original plan was to make 20 pieces a day and complete them in 7 days. As a result, the task is completed in 5 days, how many pieces are done on average per day? (Solve with ratio)
同学们为幼儿园小朋友做一批小玩具，原计划每天做20件，7天完成．结果5天完成任务，平均每天做多少件？(用比例解)
<gadget id="calculator">20 * 7</gadget>
<output>140</output>

<gadget id="calculator">140 / 5</gadget>
<output>28</output>

<result>28</result>