Xi'an held a calligraphy and painting competition for primary school students, with a number of first, second and third prizes. The first and second prizes accounted for (2/7) of the total number of winners, and the second and third prizes accounted for (2/7) of the total number of winners. 9/10), what percentage of the total number of winners won the second prize?
西安市举办一次小学生书画大赛，设一、二、三等奖若干名，获一、二等奖的占获奖总人数的(2/7)，获二、三等奖的占获奖总人数的(9/10)，获二等奖的占获奖总人数的几分之几？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

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

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (5/7) - (1/10)</gadget>
<output>13/70 = around 0.185714</output>

<result>13/70 = around 0.185714</result>