A machine factory produces a batch of machines. It originally planned to produce 40 machines per day, and the production task was completed in 20 days. The production task was actually completed 4 days ahead of schedule. How many machines are actually produced per day?
一个机器厂生产一批机器，原计划每天生产40台机器，20天完成生产任务，实际提前了4天就完成了生产任务，实际每天生产多少台机器？
<gadget id="calculator">40 * 20</gadget>
<output>800</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">800 / 16</gadget>
<output>50</output>

<result>50</result>