Xiaohua reads an inspirational book. He reads 25% of the whole book on the first day and 50 pages on the second day. At this time, the number of pages he has read is 5/7 of the remaining pages. How much is Xiaohua left? Page not read?
小华读一本励志书，第一天读了全书的25%，第二天读了50页，这时已读的页数是余下的页数的(5/7)，小华还有多少页没有读？
<gadget id="calculator">5 + 7</gadget>
<output>12</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(5/12) - (1/4)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">50 / (1/6)</gadget>
<output>300</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">300 * (7/12)</gadget>
<output>175</output>

<result>175</result>