The school holds a sports meeting (one person can only participate in one event). Those who participated in long-distance running accounted for (1/2) of the total number of people, those who participated in long-distance running accounted for (1/5) of the total number of people, and those who participated in long-distance jumping accounted for (2/7) of the total number of people. ? What percentage of the total number of people did not participate in these three projects?
学校举行运动会(一人只能参加一个项目)．参加长跑的占总人数的(1/2)，投掷的占总人数的(1/5)，跳远的占总人数的(2/7)，参加长跑的比投掷和跳远的多几分之几？没参加这三个项目的人占总人数的几分之几？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(1/2) + (1/5) + (2/7)</gadget>
<output>69/70 = around 0.985714</output>

<gadget id="calculator">1 - (69/70)</gadget>
<output>1/70 = around 0.014286</output>

<result>1/70 = around 0.014286</result>