Master Li needs to produce 400 parts, and 75% of them have been produced. How many parts must be produced to complete the task?
李师傅要生产400个零件，已经生产了75%，还要生产多少个零件才能完成任务？
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">400 * (1/4)</gadget>
<output>100</output>

<result>100</result>