The TV factory originally planned to produce a batch of TVs in 20 days, but actually produced 25 sets a day, and completed the task 4 days ahead of schedule. How many TVs are there in this batch?
电视机厂原计划20天生产一批电视，实际每天生产25台，提前4天完成了任务．这批电视机有多少台？
<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">16 * 25</gadget>
<output>400</output>

<result>400</result>