An Olympic school in a certain city conducts a quick calculation competition. A total of 1,000 questions are given. A can calculate 30 questions per minute. B can calculate 50 questions in 3 seconds less than A can calculate the same number of questions. How many questions are not done.
某市奥林匹克学校进行速算比赛，共出了1000道题，甲每分可算出30道题，乙每算出50道题比甲算同样多的题少用3秒，乙做完1000题，甲还有多少题没有做出．
<gadget id="calculator">1_000 / 50</gadget>
<output>20</output>

<gadget id="calculator">50 / 30</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(5/3) - (1/20)</gadget>
<output>97/60 = around 1.616667</output>

<gadget id="calculator">30 * 20 * (97/60)</gadget>
<output>970</output>

<gadget id="calculator">1_000 - 970</gadget>
<output>30</output>

<result>30</result>