The day before yesterday, Xiaoguang logged on to the website www.mathematicsworld.com. mqw91． com, he saw "How did you know about this website?" survey on the page, he checked the voting results, and found that the total number of voters was 500, and the voting rate for the item "Magazine" was 68%. When he logged on to the Mathematics World website again yesterday, he found that the voting rate for the item "Magazine" had risen to 72%, so what was the total number of voters at that time?
小光前天登录到数理天地网站www．mqw91．com，他在页面看到"您是通过什么方式知道本网站的？"调查，他查看了投票结果，发现投票总人数是500人，"杂志"项的投票率是68%．当他昨天再次登录数理天地网站时，发现"杂志"项的投票率上升到72%，则当时的投票总人数至少是多少．
<gadget id="calculator">25 * 3</gadget>
<output>75</output>

<gadget id="calculator">500 + 75</gadget>
<output>575</output>

<result>575</result>