In physical education class, some students are sitting and some are standing. At this time, 25% of the sitting people stood up, 25% of the standing people sat down, and 70% of the standing people. Ask what percentage of the total number of people were standing?
体育课上一些同学坐着，一些人站着．此时，坐着的25%人站起来，站着的25%人坐下，站着的人占总人数的70%．问原来站着的人占总人数的百分之几？
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

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

<gadget id="calculator">(7/10) - (1/4)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(3/4) - (7/10)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(9/20) / (1/20)</gadget>
<output>9</output>

<gadget id="calculator">1 + 9</gadget>
<output>10</output>

<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>