Xiaoxue and Xiaoxu competed in oral calculations. There were 1200 questions in total. Xiaoxue calculated 20 questions per minute. Xiaoxu took 4 seconds less than Xiaoxue to calculate the same number of questions for every 80 questions. Question: When Xiaoxu finished 1200 questions, what did Xiaoxue How many questions are left?
小雪和小序两人比赛口算，共有1200题，小雪每分算出20题，小序每算出80题比小雪算同样多的题少用了4秒，问：小序做完1200题时，小雪还有多少题没做？
<gadget id="calculator">1_200 / 80</gadget>
<output>15</output>

<gadget id="calculator">4 / 60</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">15 * (1/15) * 20</gadget>
<output>20</output>

<result>20</result>